ACM-ICPC 2018 沈阳赛区网络预赛 F. Fantastic Graph (贪心)

Posted 2021-01-04 xiuwenli

分析:贪心地删边后检查每个点的度即可,这也是正确的做法?

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e4+5;
struct Edge{
    int u,v,next;
}edges[MAXN<<2];
int head[MAXN],tot;
int deg[MAXN];

void init()
{
    memset(head,-1,sizeof(head));
    tot =0 ;
    memset(deg,0,sizeof(deg));
}

void AddEdge(int u,int v)
{
    edges[tot] = (Edge){u,v,head[u]};
    head[u] = tot++;
}

int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif
    int cas = 1;
    int N,M,K,u,v;
    while(scanf("%d %d %d",&N,&M,&K)==3){
        init();
        memset(deg,0,sizeof(deg));
        int L,R; scanf("%d %d",&L, &R);

        for(int i=1;i<=K;++i){
            scanf("%d %d",&u,&v);
            v+=N;
            AddEdge(u,v);
            deg[u]++;  deg[v]++;
        }

        for(int e=0;e<tot;++e){
            u = edges[e].u, v =edges[e].v;
            if(deg[u]>R || deg[v]>R){
                deg[u]--;
                deg[v]--;
            }
        }

        bool flag = true;

        for(int i=1;i<=N+M;++i){
            if(deg[i]<L || deg[i]>R){
                flag = false;
                break;
            }
        }
        printf("Case %d: ",cas++);
        if(flag) printf("Yes
");
        else printf("No
");
    }
    return 0;
}