k보다 작거나 같은 BST의 가장 큰 숫자

k보다 작거나 같은 BST의 가장 큰 숫자

a의 루트를 고려하면 이진 검색 트리 그리고 정수 케이 . 임무는 다음을 찾는 것입니다. 가장 큰 수 이진 검색 트리에서 미만 또는 동일한 그러한 요소가 존재하지 않으면 k에 -1을 인쇄합니다. 

예:  

입력:

K-1보다 작거나 같은 BST의 가장 큰 숫자

출력 : 21
설명 : 19와 25는 21에 가장 가까운 두 숫자이고 19는 21보다 작거나 같은 값을 갖는 가장 큰 숫자입니다.

입력:

K-2보다 작거나 같은 BST의 가장 큰 숫자

출력 : 3
설명 : 3과 5는 4에 가장 가까운 두 수이고, 3은 4보다 작거나 같은 값을 갖는 가장 큰 수입니다.

목차

[순진한 접근 방식] 재귀 사용 - O(h) 시간 및 O(h) 공간

아이디어는 다음부터 시작하는 것입니다. 뿌리 그리고 그 값을 k와 비교합니다. 노드의 값이 k보다 크면 왼쪽 하위 트리로 이동합니다. 그렇지 않으면 k보다 작은 가장 큰 숫자의 값을 찾으십시오. 오른쪽 하위 트리 . 오른쪽 하위 트리가 -1을 반환하면(해당 값이 없음을 의미) 현재 노드의 값을 반환합니다. 그렇지 않으면 오른쪽 하위 트리에서 반환된 값을 반환합니다(현재 노드의 값보다 크지만 k보다 작기 때문입니다).

C++
   // C++ code to find the largest value    // smaller than or equal to k using recursion   #include          using     namespace     std  ;   class     Node     {   public  :      int     data  ;      Node     *  left       *  right  ;          Node  (  int     val  ){      data     =     val  ;      left     =     nullptr  ;      right     =     nullptr  ;      }   };   // function to find max value less than k   int     findMaxFork  (  Node  *     root       int     k  )     {          // Base cases      if     (  root     ==     nullptr  )      return     -1  ;      if     (  root  ->  data     ==     k  )      return     k  ;      // If root's value is smaller      // try in right subtree      else     if     (  root  ->  data      <     k  )     {          int     x     =     findMaxFork  (  root  ->  right       k  );      if     (  x     ==     -1  )      return     root  ->  data  ;      else      return     x  ;      }      // If root's data is greater       // return value from left subtree.      return     findMaxFork  (  root  ->  left       k  );      }   int     main  ()     {          int     k     =     24  ;      // creating following BST      //      // 5      // /        // 2 12      // /  /        // 1 3 9 21      // /        // 19 25      Node  *     root     =     new     Node  (  5  );      root  ->  left     =     new     Node  (  2  );      root  ->  left  ->  left     =     new     Node  (  1  );      root  ->  left  ->  right     =     new     Node  (  3  );      root  ->  right     =     new     Node  (  12  );      root  ->  right  ->  left     =     new     Node  (  9  );      root  ->  right  ->  right     =     new     Node  (  21  );      root  ->  right  ->  right  ->  left     =     new     Node  (  19  );      root  ->  right  ->  right  ->  right     =     new     Node  (  25  );          cout      < <     findMaxFork  (  root       k  );      return     0  ;   }   
Java
   // Java code to find the largest value    // smaller than or equal to k using recursion   class   Node     {      int     data  ;      Node     left       right  ;          Node  (  int     val  )     {      data     =     val  ;      left     =     null  ;      right     =     null  ;      }   }   class   GfG     {          // function to find max value less than k      static     int     findMaxFork  (  Node     root       int     k  )     {          // Base cases      if     (  root     ==     null  )      return     -  1  ;      if     (  root  .  data     ==     k  )      return     k  ;      // If root's value is smaller      // try in right subtree      else     if     (  root  .  data      <     k  )     {      int     x     =     findMaxFork  (  root  .  right       k  );      if     (  x     ==     -  1  )      return     root  .  data  ;      else      return     x  ;      }      // If root's data is greater      // return value from left subtree.      return     findMaxFork  (  root  .  left       k  );      }      public     static     void     main  (  String  []     args  )     {      int     k     =     24  ;      // creating following BST      //      // 5      // /        // 2 12      // /  /        // 1 3 9 21      // /        // 19 25      Node     root     =     new     Node  (  5  );      root  .  left     =     new     Node  (  2  );      root  .  left  .  left     =     new     Node  (  1  );      root  .  left  .  right     =     new     Node  (  3  );      root  .  right     =     new     Node  (  12  );      root  .  right  .  left     =     new     Node  (  9  );      root  .  right  .  right     =     new     Node  (  21  );      root  .  right  .  right  .  left     =     new     Node  (  19  );      root  .  right  .  right  .  right     =     new     Node  (  25  );      System  .  out  .  println  (  findMaxFork  (  root       k  ));      }   }   
Python
   # Python code to find the largest value    # smaller than or equal to k using recursion   class   Node  :   def   __init__  (  self     val  ):   self  .  data   =   val   self  .  left   =   None   self  .  right   =   None   # function to find max value less than k   def   findMaxFork  (  root     k  ):   # Base cases   if   root   is   None  :   return   -  1   if   root  .  data   ==   k  :   return   k   # If root's value is smaller   # try in right subtree   elif   root  .  data    <   k  :   x   =   findMaxFork  (  root  .  right     k  )   if   x   ==   -  1  :   return   root  .  data   else  :   return   x   # If root's data is greater   # return value from left subtree.   return   findMaxFork  (  root  .  left     k  )   if   __name__   ==   '__main__'  :   k   =   24   # creating following BST   #   # 5   # /     # 2 12   # /  /     # 1 3 9 21   # /     # 19 25   root   =   Node  (  5  )   root  .  left   =   Node  (  2  )   root  .  left  .  left   =   Node  (  1  )   root  .  left  .  right   =   Node  (  3  )   root  .  right   =   Node  (  12  )   root  .  right  .  left   =   Node  (  9  )   root  .  right  .  right   =   Node  (  21  )   root  .  right  .  right  .  left   =   Node  (  19  )   root  .  right  .  right  .  right   =   Node  (  25  )   print  (  findMaxFork  (  root     k  ))   
C#
   // C# code to find the largest value    // smaller than or equal to k using recursion   using     System  ;   class     Node     {      public     int     data  ;      public     Node     left       right  ;          public     Node  (  int     val  )     {      data     =     val  ;      left     =     null  ;      right     =     null  ;      }   }   class     GfG     {          // function to find max value less than k      static     int     FindMaxFork  (  Node     root       int     k  )     {          // Base cases      if     (  root     ==     null  )      return     -  1  ;      if     (  root  .  data     ==     k  )      return     k  ;      // If root's value is smaller      // try in right subtree      else     if     (  root  .  data      <     k  )     {      int     x     =     FindMaxFork  (  root  .  right       k  );      if     (  x     ==     -  1  )      return     root  .  data  ;      else      return     x  ;      }      // If root's data is greater      // return value from left subtree.      return     FindMaxFork  (  root  .  left       k  );      }      static     void     Main  ()     {      int     k     =     24  ;      // creating following BST      //      // 5      // /        // 2 12      // /  /        // 1 3 9 21      // /        // 19 25      Node     root     =     new     Node  (  5  );      root  .  left     =     new     Node  (  2  );      root  .  left  .  left     =     new     Node  (  1  );      root  .  left  .  right     =     new     Node  (  3  );      root  .  right     =     new     Node  (  12  );      root  .  right  .  left     =     new     Node  (  9  );      root  .  right  .  right     =     new     Node  (  21  );      root  .  right  .  right  .  left     =     new     Node  (  19  );      root  .  right  .  right  .  right     =     new     Node  (  25  );      Console  .  WriteLine  (  FindMaxFork  (  root       k  ));      }   }   
JavaScript
   // JavaScript code to find the largest value    // smaller than or equal to k using recursion   class     Node     {      constructor  (  val  )     {      this  .  data     =     val  ;      this  .  left     =     null  ;      this  .  right     =     null  ;      }   }   // function to find max value less than k   function     findMaxFork  (  root       k  )     {          // Base cases      if     (  root     ===     null  )      return     -  1  ;      if     (  root  .  data     ===     k  )      return     k  ;      // If root's value is smaller      // try in right subtree      else     if     (  root  .  data      <     k  )     {      let     x     =     findMaxFork  (  root  .  right       k  );      if     (  x     ===     -  1  )      return     root  .  data  ;      else      return     x  ;      }      // If root's data is greater      // return value from left subtree.      return     findMaxFork  (  root  .  left       k  );   }   let     k     =     24  ;   // creating following BST   //   // 5   // /     // 2 12   // /  /     // 1 3 9 21   // /     // 19 25   let     root     =     new     Node  (  5  );   root  .  left     =     new     Node  (  2  );   root  .  left  .  left     =     new     Node  (  1  );   root  .  left  .  right     =     new     Node  (  3  );   root  .  right     =     new     Node  (  12  );   root  .  right  .  left     =     new     Node  (  9  );   root  .  right  .  right     =     new     Node  (  21  );   root  .  right  .  right  .  left     =     new     Node  (  19  );   root  .  right  .  right  .  right     =     new     Node  (  25  );   console  .  log  (  findMaxFork  (  root       k  ));   

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[예상 접근 방식] Iteration을 활용 - O(h) 시간과 O(1) 공간

아이디어는 다음부터 시작하는 것입니다. 뿌리 그리고 그 값을 다음과 비교해보세요. 케이 . 노드의 값이 다음과 같은 경우 <= k 결과 값을 루트 값으로 업데이트하고 오른쪽 그렇지 않으면 하위 트리로 이동합니다. 왼쪽 하위 트리. 에 의해 반복적으로 모든 노드에 이 작업을 적용하면 필요한 공간을 최소화할 수 있습니다. 재귀 스택.

C++
   // C++ code to find the largest value    // smaller than or equal to k using recursion   #include          using     namespace     std  ;   class     Node     {   public  :      int     data  ;      Node     *  left       *  right  ;          Node  (  int     val  ){      data     =     val  ;      left     =     nullptr  ;      right     =     nullptr  ;      }   };   // function to find max value less than k   int     findMaxFork  (  Node  *     root       int     k  )     {          int     result     =     -1  ;          // Start from root and keep looking for larger       while     (  root     !=     nullptr  )     {      // If root is smaller go to right side      if     (  root  ->  data      <=     k  ){      result     =     root  ->  data  ;      root     =     root  ->  right  ;      }      // If root is greater go to left side       else      root     =     root  ->  left  ;      }          return     result  ;   }   int     main  ()     {          int     k     =     24  ;      // creating following BST      //      // 5      // /        // 2 12      // /  /        // 1 3 9 21      // /        // 19 25      Node  *     root     =     new     Node  (  5  );      root  ->  left     =     new     Node  (  2  );      root  ->  left  ->  left     =     new     Node  (  1  );      root  ->  left  ->  right     =     new     Node  (  3  );      root  ->  right     =     new     Node  (  12  );      root  ->  right  ->  left     =     new     Node  (  9  );      root  ->  right  ->  right     =     new     Node  (  21  );      root  ->  right  ->  right  ->  left     =     new     Node  (  19  );      root  ->  right  ->  right  ->  right     =     new     Node  (  25  );          cout      < <     findMaxFork  (  root       k  );      return     0  ;   }   
Java
   // Java code to find the largest value    // smaller than or equal to k using recursion   class   Node     {      int     data  ;      Node     left       right  ;          Node  (  int     val  )     {      data     =     val  ;      left     =     null  ;      right     =     null  ;      }   }   class   GfG     {          // function to find max value less than k      static     int     findMaxFork  (  Node     root       int     k  )     {      int     result     =     -  1  ;          // Start from root and keep looking for larger       while     (  root     !=     null  )     {      // If root is smaller go to right side      if     (  root  .  data      <=     k  )     {      result     =     root  .  data  ;      root     =     root  .  right  ;      }      // If root is greater go to left side       else     {      root     =     root  .  left  ;      }      }          return     result  ;      }      public     static     void     main  (  String  []     args  )     {      int     k     =     24  ;      // creating following BST      //      // 5      // /        // 2 12      // /  /        // 1 3 9 21      // /        // 19 25      Node     root     =     new     Node  (  5  );      root  .  left     =     new     Node  (  2  );      root  .  left  .  left     =     new     Node  (  1  );      root  .  left  .  right     =     new     Node  (  3  );      root  .  right     =     new     Node  (  12  );      root  .  right  .  left     =     new     Node  (  9  );      root  .  right  .  right     =     new     Node  (  21  );      root  .  right  .  right  .  left     =     new     Node  (  19  );      root  .  right  .  right  .  right     =     new     Node  (  25  );      System  .  out  .  println  (  findMaxFork  (  root       k  ));      }   }   
Python
   # Python code to find the largest value    # smaller than or equal to k using recursion   class   Node  :   def   __init__  (  self     val  ):   self  .  data   =   val   self  .  left   =   None   self  .  right   =   None   # function to find max value less than k   def   findMaxFork  (  root     k  ):   result   =   -  1   # Start from root and keep looking for larger    while   root   is   not   None  :   # If root is smaller go to right side   if   root  .  data    <=   k  :   result   =   root  .  data   root   =   root  .  right   # If root is greater go to left side    else  :   root   =   root  .  left   return   result   if   __name__   ==   '__main__'  :   k   =   24   # creating following BST   #   # 5   # /     # 2 12   # /  /     # 1 3 9 21   # /     # 19 25   root   =   Node  (  5  )   root  .  left   =   Node  (  2  )   root  .  left  .  left   =   Node  (  1  )   root  .  left  .  right   =   Node  (  3  )   root  .  right   =   Node  (  12  )   root  .  right  .  left   =   Node  (  9  )   root  .  right  .  right   =   Node  (  21  )   root  .  right  .  right  .  left   =   Node  (  19  )   root  .  right  .  right  .  right   =   Node  (  25  )   print  (  findMaxFork  (  root     k  ))   
C#
   // C# code to find the largest value    // smaller than or equal to k using recursion   using     System  ;   class     Node     {      public     int     data  ;      public     Node     left       right  ;          public     Node  (  int     val  )     {      data     =     val  ;      left     =     null  ;      right     =     null  ;      }   }   class     GfG     {          // function to find max value less than k      static     int     FindMaxFork  (  Node     root       int     k  )     {      int     result     =     -  1  ;          // Start from root and keep looking for larger       while     (  root     !=     null  )     {      // If root is smaller go to right side      if     (  root  .  data      <=     k  )     {      result     =     root  .  data  ;      root     =     root  .  right  ;      }      // If root is greater go to left side       else     {      root     =     root  .  left  ;      }      }          return     result  ;      }      static     void     Main  ()     {      int     k     =     24  ;      // creating following BST      //      // 5      // /        // 2 12      // /  /        // 1 3 9 21      // /        // 19 25      Node     root     =     new     Node  (  5  );      root  .  left     =     new     Node  (  2  );      root  .  left  .  left     =     new     Node  (  1  );      root  .  left  .  right     =     new     Node  (  3  );      root  .  right     =     new     Node  (  12  );      root  .  right  .  left     =     new     Node  (  9  );      root  .  right  .  right     =     new     Node  (  21  );      root  .  right  .  right  .  left     =     new     Node  (  19  );      root  .  right  .  right  .  right     =     new     Node  (  25  );      Console  .  WriteLine  (  FindMaxFork  (  root       k  ));      }   }   
JavaScript
   // JavaScript code to find the largest value    // smaller than or equal to k using recursion   class     Node     {      constructor  (  val  )     {      this  .  data     =     val  ;      this  .  left     =     null  ;      this  .  right     =     null  ;      }   }   // function to find max value less than k   function     findMaxFork  (  root       k  )     {      let     result     =     -  1  ;          // Start from root and keep looking for larger       while     (  root     !==     null  )     {      // If root is smaller go to right side      if     (  root  .  data      <=     k  )     {      result     =     root  .  data  ;      root     =     root  .  right  ;      }      // If root is greater go to left side       else     {      root     =     root  .  left  ;      }      }          return     result  ;   }   let     k     =     24  ;   // creating following BST   //   // 5   // /     // 2 12   // /  /     // 1 3 9 21   // /     // 19 25   let     root     =     new     Node  (  5  );   root  .  left     =     new     Node  (  2  );   root  .  left  .  left     =     new     Node  (  1  );   root  .  left  .  right     =     new     Node  (  3  );   root  .  right     =     new     Node  (  12  );   root  .  right  .  left     =     new     Node  (  9  );   root  .  right  .  right     =     new     Node  (  21  );   root  .  right  .  right  .  left     =     new     Node  (  19  );   root  .  right  .  right  .  right     =     new     Node  (  25  );   console  .  log  (  findMaxFork  (  root       k  ));   

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