# 34.二叉树中和为某一值的路径

## 题目

输入一棵二叉树和一个整数，打印出二叉树中节点值的和为输入整数的所有路径。从树的根节点开始往下一直到叶节点所经过的节点形成一条路径。

示例: 给定如下二叉树，以及目标和 target = 22，

```
               5
              / \
             4   8
            /   / \
           11  13  4
          /  \    / \
         7    2  5   1
```

返回:

```
 [
    [5,4,11,2],
    [5,8,4,5]
 ]
```

提示：

节点总数 <= 10000

来源：[力扣（LeetCode）](https://leetcode-cn.com/problems/er-cha-shu-zhong-he-wei-mou-yi-zhi-de-lu-jing-lcof)

## 题解

将问题拆解为子树的问题，递归解决

```swift
func pathSum(_ root: TreeNode?, _ target: Int) -> [[Int]] {
    guard let rootV = root?.val else {
        return []
    }
    var result: [[Int]] = []
    let deta = target - rootV
    var temp: [TreeNode] = []

    if let left = root?.left {
        temp.append(left)
    }

    if let right = root?.right {
        temp.append(right)
    }

    if temp.isEmpty { // 到达叶节点了
        if target == rootV {
            result.append([rootV])
        }
    }
    else {
        temp.forEach { tree in
            pathSum(tree, deta).forEach { datas in
                result.append([rootV] + datas)
            }
        }
    }

    return result
}
```

![01](/files/-MiuwlJEJZR37OZjmvO-)


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