Import Spaghetti

来源：互联网发布：app的运营数据分析编辑：程序博客网时间：2024/06/14 17:56
题意：给你一个有向图，输出其中的最小环
解题思路：数据只有500，暴力即可
#include <iostream>#include <cstdio>#include <cstring>#include <string>#include <algorithm>#include <cmath>#include <map>#include <set>#include <stack>#include <queue>#include <vector>#include <bitset>#include <functional>using namespace std;#define LL long longconst int INF = 0x3f3f3f3f;map<string,int> mp;char ch[100010], name[505][10], s[20];int f[505],nt[250009],e[250009];int n,cnt,x;int p[510],dis[510];int bfs(int root){    memset(dis, INF, sizeof dis);    bool flag = true;    queue<int> q;    q.push(root);    while(!q.empty())    {        int pre = q.front();        q.pop();        if(pre==root)        {            if(!flag) return dis[root];            else flag = false;        }        for(int i=f[pre]; ~i; i=nt[i])        {            int temp;            if(pre==root) temp = 1;            else temp = dis[pre] + 1;            if(dis[e[i]] > temp)            {                q.push(e[i]);                dis[e[i]] = temp;            }        }    }    return INF;}int main(){    while(~scanf("%d",&n))    {        cnt=0;        memset(f,-1,sizeof f);        mp.clear();        for(int i=1; i<=n; i++)        {            scanf("%s",name[i]);            mp[name[i]] = i;        }        for(int i=1; i<=n; i++)        {            scanf("%s%d",name[i],&x);            for(int j=1; j<=x; j++)            {                scanf("%s",ch);                getchar();                gets(ch);                int tot = 0;                int len = strlen(ch);                for(int k=0; k<len; k++)                {                    if(ch[k] == ',')                    {                        s[tot] = '\0';                        nt[cnt]=f[mp[s]],f[mp[s]]=cnt,e[cnt++]=i;                        k++;                        tot=0;                    }                    else s[tot++]=ch[k];                }                s[tot]='\0';                nt[cnt]=f[mp[s]],f[mp[s]]=cnt,e[cnt++]=i;            }        }        int pos = -1, mi = INF;        for(int i=1; i<=n;i++)        {            int temp = bfs(i);            if(temp < mi)            {                mi = temp;                pos = i;            }        }        if(mi == INF)        {            printf("SHIP IT\n");            continue;        }        queue<int> q;        q.push(pos);        memset(dis, INF, sizeof dis);        while(!q.empty())        {            int pre = q.front();            q.pop();            int flag=0;            for(int i=f[pre]; ~i; i=nt[i])            {                int temp;                if(pre == pos) temp = 1;                else temp = dis[pre] + 1;                if(dis[e[i]] > temp)                {                    p[e[i]] = pre;                    q.push(e[i]);                    dis[e[i]] = temp;                }                if(e[i] == pos)                {                    p[pos] = pre;                    flag=1;                    break;                }            }            if(flag) break;        }        int temp = pos;        while(p[temp] != pos)        {            printf("%s ",name[p[temp]]);            temp = p[temp];        }        printf("%s\n",name[pos]);    }    return 0;}
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