1. 程式人生 > >lintcode——把排序陣列轉換為高度最小的二叉搜尋樹

lintcode——把排序陣列轉換為高度最小的二叉搜尋樹

/**
 * Definition of TreeNode:
 * class TreeNode {
 * public:
 *     int val;
 *     TreeNode *left, *right;
 *     TreeNode(int val) {
 *         this->val = val;
 *         this->left = this->right = NULL;
 *     }
 * }
 */
class Solution {
public:
    /**
     * @param A: A sorted (increasing order) array
     * @return: A tree node
     */
    TreeNode *ToBST(vector<int> &T,int a,int c)     //需要呼叫的函式,開始轉換
    { 
        if(a>c)
            return NULL;
        else{
              int b=(a+c)/2;
              TreeNode *root=new TreeNode(T[b]);
              root->left=ToBST(T,a,b-1);
              root->right=ToBST(T,b+1,c);
              return root;
        }
    }
   
    TreeNode *sortedArrayToBST(vector<int> &A) {
        // write your code here
        if(A.empty())
           return NULL;
        else
          {  int begin=0,end=A.size()-1,mid=(begin+end)/2;
             TreeNode *root=new TreeNode(A[mid]);
             root->left=ToBST(A,begin,mid-1);     //呼叫函式
             root->right=ToBST(A,mid+1,end);    //呼叫函式
             return root;
           }
        }
};