LeetCode——Minimum Depth of Binary Tree

题目：
Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

解答：

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    int minDepth(TreeNode* root) {        if (root == NULL) {            return 0;        }        stack<TreeNode*> nodeStack;        stack<int> deptStack;        int curMinDepth = INT_MAX;        nodeStack.push(root);        deptStack.push(1);        while (!nodeStack.empty()) {            TreeNode* top = nodeStack.top();            int curDept = deptStack.top();            nodeStack.pop();            deptStack.pop();            if (top->left == NULL && top->right == NULL) {                curMinDepth = curMinDepth > curDept ? curDept : curMinDepth;            }             if (curDept < curMinDepth) {                if (top->left) {                    nodeStack.push(top->left);                     deptStack.push(curDept + 1);                }                 if (top->right) {                   nodeStack.push(top->right);                    deptStack.push(curDept + 1);                }            }        }        return curMinDepth;    }};