wenbao与搜索

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http://agc013.contest.atcoder.jp/tasks/agc013_b

给n个点，m条边，找一条路径，要求与首尾相连的所有点必须在路径里面

两次dfs搞定（仔细体会为什么？）

很好的一个题

#include <iostream>
#include <vector>
using namespace std;
const int maxn = 1e5+10;
vector<int> v[maxn];
bool vis[maxn];
int a[maxn], num;
void d(int x){
    for(int i = 0; i < v[x].size(); ++i){
        int xx = v[x][i];
        if(vis[xx]) continue;
        vis[xx] = true, a[++num] = xx;
        d(xx); return ;
    }
}
int main(){
    int n, m, x, y, num2;
    scanf("%d%d", &n, &m);
    for(int i = 0; i < m; ++i){
        scanf("%d%d", &x, &y);
        v[x].push_back(y), v[y].push_back(x);
    }
    vis[1] = true;
    a[num = 1] =  1;
    d(1),  num2 = num, d(1);
    printf("%d
", num);
    for(int i = num2; i >= 1; --i){
        if(i == num2) printf("%d", a[i]);
        else printf(" %d", a[i]);
    }
    for(int i = num2+1; i <= num; ++i){
        printf(" %d", a[i]);
    }
    printf("
");
    return 0;
}

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只有不断学习才能进步！