1053 Path of Equal Weight

大致题意就是给出一棵树，求出叶子结点的带权路径长度等于 S的路径（即根结点到叶子结点的路径上的点权权值之和），如果有多条路径序列，那么按反字典序输出它们。

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
const int maxn = 200;
struct Node {
    int weight;
    vector<int> child;
} node[maxn];

vector<int> v;
int n,m,s;
bool cmp(const int& a, const int& b) { //把孩子结点按权值递减排序
    return node[a].weight > node[b].weight;
}
void DFS(int root,int nowSum) { //树的先序遍历 
    if(node[root].child.size() == 0) { //叶子节点
        if(nowSum == s) { //叶子结点的带权路径之和 等于 S 
            for(int i = 0; i < v.size(); ++i) {
                if(i > 0) printf(" ");
                printf("%d",node[v[i]].weight);
            }
            printf("\n");
        }
        return ;
    }
    for(int i = 0; i < node[root].child.size(); ++i) {
        int child = node[root].child[i];
        v.push_back(child); //孩子结点入栈 
        DFS(child,nowSum + node[child].weight);
        v.pop_back();//出栈 
    }
}

int main() {
    cin>>n>>m>>s;
    for(int i = 0; i < n; ++i) //初始化每个结点的权值
        cin>>node[i].weight;
    for(int i = 0; i < m; ++i) { //构造一棵树 
        int parent,k,child;
        cin>>parent>>k;
        for(int j = 0; j < k; ++j) {
            cin>>child;
            node[parent].child.push_back(child);
        }
        sort(node[parent].child.begin(),node[parent].child.end(),cmp);//把孩子结点按权值递减排序，方便后序按字典递减序输出路径
    }
    v.push_back(0); //根结点入栈 
    DFS(0,node[0].weight);
    return 0;
}