剑指offer-面试题25：二叉树中和为某一值的路径

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题目

输入一棵二叉树和一个整数，打印出二叉树中结点值的和为输入整数的所有路径。从树的根结点开始往下一直到叶结点所经过的结点形成一条路径。二叉树的定义如下：

class TreeNode {    int val;    TreeNode left;    TreeNode right;    TreeNode(int x) { val = x; }    public TreeNode() {        // TODO Auto-generated constructor stub    }

解

package Chapter4;import java.util.Stack;public class FindPathInBinaryTree {    public void findPath(TreeNode root,int expectedSum){        if(root==null)            return;        Stack<Integer> path=new Stack<Integer>();        int currentSum=0;        findPath2(root,expectedSum,path,currentSum);    }    public void findPath2(TreeNode root, int expectedSum, Stack<Integer> path, int currentSum) {        // TODO Auto-generated method stub        currentSum+=root.val;        path.push(root.val);        //如果是叶结点，并且路径上结点的和等于输入的值        //打印出这条路径        boolean isLeaf=root.left==null&&root.right==null;        if(currentSum==expectedSum&&isLeaf){            System.out.print("A path is found:");            for(Integer i:path){                System.out.print(i+"  ");                           }                       System.out.println("");        }        //如果不是叶结点，则遍历它的子结点        if(root.left!=null){            findPath2(root.left,expectedSum,path,currentSum);        }        if(root.right!=null){            findPath2(root.right,expectedSum,path,currentSum);        }        //在返回到父结点之前，在路径上删除当前结点        currentSum-=root.val;        path.pop();    }    public static void main(String[] args) {        // TODO Auto-generated method stub        TreeNode root=new TreeNode(10);        TreeNode Node5=new TreeNode(5);        TreeNode Node12=new TreeNode(12);        TreeNode Node4=new TreeNode(4);        TreeNode Node7=new TreeNode(7);        root.left=Node5;        root.right=Node12;        Node5.left=Node4;        Node5.right=Node7;        FindPathInBinaryTree fP=new FindPathInBinaryTree();             fP.findPath(root, 22);    }}class TreeNode {    int val;    TreeNode left;    TreeNode right;    TreeNode(int x) { val = x; }    public TreeNode() {        // TODO Auto-generated constructor stub    }}

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