路径总和 · 交互式算法学习

这是一组同题正确实现，独立于上方当前动画方法；不同语言可能采用另一种正确策略。

1/**2 * Definition for a binary tree node.3 * public class TreeNode {4 *     int val;5 *     TreeNode left;6 *     TreeNode right;7 *     TreeNode() {}8 *     TreeNode(int val) { this.val = val; }9 *     TreeNode(int val, TreeNode left, TreeNode right) {10 *         this.val = val;11 *         this.left = left;12 *         this.right = right;13 *     }14 * }15 */16class Solution {17    public boolean hasPathSum(TreeNode root, int targetSum) {18        return dfs(root, targetSum);19    }20 21    private boolean dfs(TreeNode root, int s) {22        if (root == null) {23            return false;24        }25        s -= root.val;26        if (root.left == null && root.right == null && s == 0) {27            return true;28        }29        return dfs(root.left, s) || dfs(root.right, s);30    }31}