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  • 30 Day Challenge Day 2 | Leetcode 1302. Deepest Leaves Sum

    题解

    非常典型的二叉树遍历的题,BFS做起来更顺手一些,DFS处理起来要稍稍注意些。

    BFS

    class Solution {
    public:
        int deepestLeavesSum(TreeNode* root) {
            if(!root) return 0;
    
            queue<TreeNode*> q;
            q.push(root);
            int sum = 0;
            
            while(!q.empty()) {
                int sz = q.size();
                sum = 0;
                for(int i = 0; i < sz; i++) {
                    TreeNode* t = q.front();
                    q.pop();
                    sum += t->val;
                    if(t->left) {
                        q.push(t->left);
                    }
                    if(t->right) {
                        q.push(t->right);
                    }
                }
            }
            
            return sum;
        }
    };
    

    DFS

    class Solution {
    public:
        int deepestLeavesSum(TreeNode* root) {
            int level = 0, deepest = 0, sum = 0;
            deepestSum(root, level, deepest, sum);
            return sum;
        }
        
        void deepestSum(TreeNode* node, int level, int &deepest, int &sum) {
            if(!node) return;
            
            level += 1;
            
            if(level == deepest) {
                sum += node->val;
            } else if (level > deepest) {
                sum = node->val;
                deepest = level;
            }
            
            deepestSum(node->left, level, deepest, sum);
            deepestSum(node->right, level, deepest, sum);
        }
    };
    
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  • 原文地址:https://www.cnblogs.com/casperwin/p/13233640.html
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