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Given a binary tree containing digits from 0-9
only, each root-to-leaf path could represent a number.
An example is the root-to-leaf path 1->2->3
which represents the number 123
.
Find the total sum of all root-to-leaf numbers.
For example,
1 / 2 3
The root-to-leaf path 1->2
represents the number 12
.
The root-to-leaf path 1->3
represents the number 13
.
Return the sum = 12 + 13 = 25
.
如果bfs不能处理 4,9,0,null,1 这种,答案会是891,因为40错误乘10了,正确答案是531 =491+40
用dfs(不知道是不是dfs)
public int sumNumbers(TreeNode root) { if(root==null) return 0; return dfs(root, 0); // 0 为传递到root这个点的时候的积累值 } private int dfs(TreeNode n, int preSum){ if(n==null) return 0; int sum = n.val+10*preSum; if(n.left==null && n.right==null) return sum; if(n.left!=null && n.right!=null) return dfs(n.left,sum)+dfs(n.right,sum); if(n.left!=null) return dfs(n.left,sum); return dfs(n.right,sum); } }
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原文地址:http://www.cnblogs.com/jiajiaxingxing/p/4567932.html