hdu 3038（How Many Answers Are Wrong）+3047（Zjnu Stadium）（种类并查集）

来源：互联网发布：阿姆斯特丹大学知乎编辑：程序博客网时间：2024/09/21 08:47

hdu 3038：http://acm.hdu.edu.cn/showproblem.php?pid=3038

hdu 3047：http://acm.hdu.edu.cn/showproblem.php?pid=3047

如果之前没见过种类并查集的话，估计第一反应都是线段树吧...

这两道题都是在压缩路径的时候，利用递归，求得节点到根的距离。

用sum[i]表示节点i到根节点的距离,f[i]记录i的根节点。

f[rb]=ra;
sum[rb]=sum[a]-sum[b]+c;()

hdu 3038 代码（去掉注释那行可以秒过3047）：

#include <limits.h>#include <math.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <time.h>#include <algorithm>#include <iostream>#include <iterator>#include <sstream>#include <queue>#include <stack>#include <string>#include <vector>#include <list>#include <set>//#define ONLINE_JUDGE#define eps 1e-6#define INF 0x7fffffff                                          //INT_MAX#define inf 0x3f3f3f3f                                          //int??????????????????#define FOR(i,a) for((i)=0;i<(a);(i)++)                          //[i,a);#define MEM(a) (memset((a),0,sizeof(a)))#define sfs(a) scanf("%s",a)#define sf(a) scanf("%d",&a)#define sfI(a) scanf("%I64d",&a)#define pf(a) printf("%d\n",a)#define pfI(a) printf("%I64d\n",a)#define pfs(a) printf("%s\n",a)#define sfd(a,b) scanf("%d%d",&a,&b)#define sft(a,b,c)scanf("%d%d%d",&a,&b,&c)#define for1(i,a,b) for(int i=(a);i<b;i++)#define for2(i,a,b) for(int i=(a);i<=b;i++)#define for3(i,a,b)for(int i=(b);i>=a;i--)#define MEM1(a) memset(a,0,sizeof(a))#define MEM2(a) memset(a,-1,sizeof(a))#define MEM3(a) memset(a,0x3f,sizeof(a))#define MEMS(a) memset(a,'\0',sizeof(a))#define LL __int64const double PI = acos(-1.0);template<class T> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }template<class T> inline T Min(T a, T b) { return a < b ? a : b; }template<class T> inline T Max(T a, T b) { return a > b ? a : b; }using namespace std;template<class T>T Mint(T a, T b, T c) {    if (a>b) {        if (c>b)            return b;        return c;    }    if (c>a)        return a;    return c;}template<class T>T Maxt(T a, T b, T c) {    if (a>b) {        if (c>a)            return c;        return a;    }    else if (c > b)        return c;    return b;}const int maxn=200010;int T,n,m;int ans,f[maxn],sum[maxn];void Make_Set(int x){    f[x]=x;    sum[x]=0;}int find(int x){    if(x!=f[x]){    int tmp=f[x];    f[x]=find(f[x]);    sum[x]+=sum[tmp];    }    return f[x];}void Union(int a,int b,int c){    int ra=find(a);    int rb=find(b);if(ra==rb){if(sum[b]-sum[a]!=c)ans++;}else{f[rb]=ra;sum[rb]=sum[a]-sum[b]+c;}}int main(){#ifndef ONLINE_JUDGE    freopen("test.in","r",stdin);    freopen("test.out","w",stdout);#endif    while(~sfd(n,m)){        for2(i,0,n)        Make_Set(i);        int a,b,c;        ans=0;        while(m--){            sft(a,b,c);            a--;//去掉这一行可以秒掉hdu 3047            Union(a,b,c);        }        pf(ans);    }    return 0;}

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