POJ 1182 食物链

来源：互联网发布：思途旅游cms源码编辑：程序博客网时间：2024/06/07 19:45

可以建立3*n的并查集，x，x+n，x+2*n分别代表一个食物圈。即若x和y属于一个类别的情况就是x和y连接，(x+n)和(y+n)连接，(x+2*n)和(y+2*n)连接；如果x吃y，那么x和(y+n)连接，(x+n)和(y+2*n)连接，(x+2*n)和y连接。依次连接即可

#include<iostream>#include<cstdio>#include<cstring>#include<ctime>#include<algorithm>#include<cstdlib>#include<cmath>#include<set>#include<bitset>#include<map>#include<stack>#include<queue>#include<vector>#include<utility>#define INF 0x3f3f3f3f#define inf 2*0x3f3f3f3f#define llinf 1000000000000000000#define pi acos(-1.0)#define mod 1000000007#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1#define lrt rt<<1#define rrt rt<<1|1#define rep(i,a,b) for(int i=(a);i<(b);i++)#define per(i,a,b) for(int i=(b)-1;i>=(a);i--)#define mem(a,b) memset(a,b,sizeof(a))#define lb(x) (x&-x)#define gi(x) scanf("%d",&x)#define gi2(x,y) scanf("%d%d",&x,&y)#define gll(x) scanf("%lld",&x)#define gll2(x,y) scanf("%lld%lld",&x,&y)#define gc(x) scanf("%c",&x)using namespace std;typedef long long ll;typedef unsigned long long ull;typedef pair<int,int>P;/***********************************************/int n,k,cnt=0,par[50005*3],ranks[50005*3],num,x,y;void init(int n){    rep(i,0,n)par[i]=i,ranks[i]=0;}int finds(int x){    if(par[x]==x)return x;    return par[x]=finds(par[x]);}void unite(int x,int y){    x=finds(x),y=finds(y);    if(x==y)return ;    if(ranks[x]>ranks[y])par[y]=x;    else par[x]=y;    if(ranks[x]==ranks[y])ranks[y]++;}bool same(int x,int y){    return finds(x)==finds(y);}int main(){    cin>>n>>k;    init(n*3);    rep(i,0,k)    {        gi(num);gi2(x,y);x--,y--;        if(x>=n||y>=n){cnt++;continue;}        if(num==1)        {            if(same(x,y+n)||same(x,y+2*n))cnt++;            else {unite(x,y),unite(x+n,y+n),unite(x+2*n,y+2*n);}        }        else        {            if(same(x,y)||same(x,y+2*n))cnt++;            else {unite(x,y+n),unite(x+n,y+2*n),unite(x+2*n,y);}        }    }    cout<<cnt;    return 0;}

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