20140711 eat 并查集

跟 食物链 完全一样

并查集即可。。

#include <cstdio>
#include <cstring>
using namespace std;
#define N 100100

int rank[3*N+100];
int par[3*N+100];
int n,m;

void init(int n) {
    for (int i=1;i<=n;i++) {
        rank[i]=0;
        par[i]=i;
    }
}

int find(int x) {
    if (par[x]==x) return x;
    return par[x]=find(par[x]);
}

void unite(int x,int y) {
    x=find(x);  y=find(y);
    if (x==y) return;
    if (rank[x]<rank[y]) par[x]=y;
    else {
        par[y]=x;
        if (rank[x]==rank[y]) x++;
    }
}

bool same(int x,int y) {
    return find(x)==find(y);
}

int main() {
    scanf("%d%d",&n,&m);
    int ans=0;
    init(3*N+10);
    for (int i=0;i<m;i++) {
        int k,x,y;
        scanf("%d%d%d",&k,&x,&y);
        if (x>N || x<1 || y>N || y<1) continue;
        if (k==1) {
            if (x==y) {
                ans++;
                continue;
            }
            if (same(x,y+N) || same(x,y+2*N))
                continue;
            else  {
                unite(x,y);
                unite(x+N,y+N);
                unite(x+2*N,y+2*N);
                ans++;
            }
        }
        else {
            if (x==y) continue;
            if (same(x,y) || same(x,y+2*N))
                continue;
            else {
                unite(x,y+N);
                unite(x+N,y+2*N);
                unite(x+2*N,y);
                ans++;
            }
        }
    }
    printf("%d",ans);
}