hdu 4284 深度优先搜索

思路：就是找能走的走，遍历一边所有情况，满足就退出。

Accepted

4284

328MS

2280K

2239 B

C++

//#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <cstring>
#include <algorithm>
#include <vector>
#define Maxn 110
#define Maxm 6000
#define LL int
#define inf 100000000
#define Abs(a) (a)>0?(a):(-a)
using namespace std;
int D[Maxn],C[Maxn],dis[Maxn][Maxn],choice[Maxn],n,m,h,vi[Maxn];
void init()
{
    memset(D,,sizeof(D));
    memset(C,,sizeof(C));
    memset(vi,,sizeof(vi));
    for(int i=;i<=;i++)
        for(int j=;j<=;j++)
        dis[i][j]=inf;
}
void floyd()
{
    int i,j,k;
    for(i=;i<=n;i++)
        dis[i][i]=;
    for(k=;k<=n;k++)
        for(i=;i<=n;i++)
        for(j=;j<=n;j++)
        dis[i][j]=min(dis[i][k]+dis[k][j],dis[i][j]);
}
int dfs(int u,int leave,int num)
{
    int i,j;
    if(num==h)
    {
        if(dis[u][]<=leave)
        return ;
        return ;
    }
    for(i=;i<=h;i++)
    if(!vi[choice[i]])
    {
        if(leave>=dis[u][choice[i]]+D[choice[i]])
        {
            vi[choice[i]]=;
            if(dfs(choice[i],leave-dis[u][choice[i]]-D[choice[i]]+C[choice[i]],num+))
                return ;
            vi[choice[i]]=;
        }
    }
    return ;
}
int main()
{
    int i,j,a,b,c,t,money;
    scanf("%d",&t);
    while(t--)
    {
        init();
        scanf("%d%d%d",&n,&m,&money);
        for(i=;i<=m;i++)
        {
            scanf("%d%d%d",&a,&b,&c);
            dis[a][b]=dis[b][a]=c<dis[a][b]?c:dis[a][b];
        }
        floyd();
        scanf("%d",&h);
        for(i=;i<=h;i++)
        {
            scanf("%d%d%d",&a,&b,&c);
            choice[i]=a,C[a]=b,D[a]=c;
        }
        for(i=;i<=h;i++)
        {
            if(!vi[choice[i]])
            {
                if(money>=dis[][choice[i]]+D[choice[i]])
                {
                    vi[choice[i]]=;
                    if(dfs(choice[i],money-dis[][choice[i]]-D[choice[i]]+C[choice[i]],))
                        break;
                    vi[choice[i]]=;
                }
            }
        }
        if(i<=h)
            printf("YES\n");
        else
            printf("NO\n");
    }
    return ;
}