leetcode-master/problems/0513.找树左下角的值.md

C++代码递归

class Solution {
public:
    int maxLen = INT_MIN;
    int maxleftValue;
    void traversal(TreeNode* root, int leftLen) {
        if (root->left == NULL && root->right == NULL) {
            if (leftLen > maxLen) {
                maxleftValue = root->val;
                maxLen = leftLen;
            }
            return;
        }
        if (root->left) {
            leftLen++;
            traversal(root->left, leftLen);
            leftLen--;
        }
        if (root->right) {
            leftLen++;
            traversal(root->right, leftLen);
            leftLen--;
        }
        return;
    }
    int findBottomLeftValue(TreeNode* root) {
        traversal(root, 0);
        return maxleftValue;
    }
};

C++代码层序遍历

class Solution {
public:
    int findBottomLeftValue(TreeNode* root) {
        queue<TreeNode*> que;
        if (root != NULL) que.push(root);
        int result = 0;
        while (!que.empty()) {
            int size = que.size();
            for (int i = 0; i < size; i++) {
                TreeNode* node = que.front();
                que.pop();
                if (i == 0) result = node->val;
                if (node->left) que.push(node->left);
                if (node->right) que.push(node->right);
            }
        }
        return result;
    }
};