紫书搜索 习题7-1 UVA

题目链接:

https://vjudge.net/problem/UVA-208

题意:

题解:

代码:

#include <bits/stdc++.h>using namespace std;typedef long long ll;#define MS(a) memset(a,0,sizeof(a))#define MP make_pair#define PB push_backconst int INF = 0x3f3f3f3f;const ll INFLL = 0x3f3f3f3f3f3f3f3fLL;inline ll read(){    ll x=0,f=1;char ch=getchar();    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}    return x*f;}//////////////////////////////////////////////////////////////////////////const int maxn = 1e5+10;int k,vis[30],vis2[30],road[30],sum;vector<int> G[maxn];bool bfs(){    queue<int> q;    q.push(1); vis[1] = 1;    while(!q.empty()){        int u = q.front(); q.pop();        if(u == k) return true;        for(int i=0; i<(int)G[u].size(); i++){            int v = G[u][i];            if(!vis[v]) {                q.push(v);                vis[v] = 1;            }        }    }    return false;}void dfs(int cur,int u){    road[cur] = u;    if(u == k){        printf("%d", road[1]);        for(int i=2; i<=cur; i++)            printf(" %d", road[i]);        puts("");        sum ++;        return ;    }    for(int i=0; i<(int)G[u].size(); i++){        int v = G[u][i];        if(!vis2[v]){            vis2[v] = 1;            dfs(cur+1,v);            vis2[v] = 0;        }    }}int main(){    int cas = 1;    while(scanf("%d",&k) == 1){        MS(vis); MS(vis2);        for(int i=0; i<=20; i++) G[i].clear();        sum = 0;        int u,v;        while(scanf("%d%d",&u,&v) && (u+v)){            G[u].push_back(v);            G[v].push_back(u);        }        for(int i=0; i<=20; i++)            sort(G[i].begin(),G[i].end());        printf("CASE %d:\n",cas++);        vis2[1] = 1;        if(bfs())  dfs(1,1);        printf("There are %d routes from the firestation to streetcorner %d.\n",sum,k);    }    return 0;}