补图上的BFS大连网络赛Sparse Graph

来源：互联网发布：linux端口流量统计编辑：程序博客网时间：2024/06/04 08:32

题意：N个点的完全图，删除M条边，问s到其他点的最短路是多少

bfs下，用set存点，若uv无边，则距离加1切把v入队

#include<iostream>#include<cstdio>#include<algorithm>#include<stack>#include<queue>#include<cstring>#include<string>#include<set>#include<map>using namespace std;typedef long long LL;const int maxn = 2e5 + 10;set<int> G[maxn];set<int> p;int n,m;int d[maxn];void solve(){    int t;    scanf("%d",&t);    while(t--)    {        p.clear();        scanf("%d%d",&n,&m);        for(int i =1;i<=n;i++)        {            p.insert(i);            G[i].clear();            d[i] = -1;        }        for(int i = 0;i<m;i++)        {            int u,v;            scanf("%d%d",&u,&v);            G[u].insert(v);            G[v].insert(u);        }        int s;        scanf("%d",&s);        p.erase(s);        d[s] = 0;        queue<int> q;        q.push(s);        while(!q.empty())        {            int t = q.front();            q.pop();            vector<int> v;            for(auto it = p.begin();it!=p.end();it++)            {                if(!G[t].count(*it))                {                    d[*it] = d[t] +1;                    q.push(*it);                    v.push_back(*it);                }            }            for(int i = 0;i<v.size();i++)            {                p.erase(v[i]);            }        }        bool flag = true;        for(int i = 1;i<=n;i++)        {            if(i==s)continue;            if(flag)            {                printf("%d",d[i]);                flag = false;            }else            {                printf(" %d",d[i]);            }        }        printf("\n");    }}int main(){    solve();    return 0;}

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