HDU 3038 How Many Answers Are Wrong 带权并查集

来源：互联网发布：德克软件编辑：程序博客网时间：2024/06/11 16:02

用par[x]表示x的根节点，用ranks[x]表示x到根节点的距离，记得每次都要更新一遍ranks数组（题目中没说有多个输入，结果改了好久才发现加上while后瞬间就ac了。。。）

#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,m,x,y,ss,cnt=0,par[200005],ranks[200005];int finds(int x){    if(par[x]==-1)return x;    int t=finds(par[x]);    ranks[x]+=ranks[par[x]];    return par[x]=t;}int main(){    while(cin>>n>>m)    {        mem(par,-1);mem(ranks,0);cnt=0;        rep(i,0,m)        {            gi2(x,y);gi(ss);x--;            int xx=finds(x),yy=finds(y);            if(xx!=yy)            {                par[yy]=xx;                ranks[yy]=ranks[x]-ranks[y]+ss;            }            else if(ranks[y]-ranks[x]!=ss)cnt++;        }        cout<<cnt<<endl;    }    return 0;}

0 0