并查集初学（2）LA 3644 & LA3027

1、LA 3644题目：http://acm.hust.edu.cn:8080/judge/problem/viewProblem.action?id=12648并查集入门题，寻找是否存在环，若存在，则cnt++

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

const int maxn=100010;

using namespace std;

int p[maxn];
//带路径压缩的并查集
int Find(int x){return p[x] == x?x:p[x]=Find(p[x]);}

int main()
{
int x,y;
while (scanf("%d",&x) == 1)
{
for (int i=0;i<maxn;i++) p[i]=i;
int cnt=0;
while (x != -1)
{
scanf("%d",&y);
x=Find(x);
y=Find(y);
if (x == y) cnt++;
else p[x]=y;
scanf("%d",&x);
}
printf("%d\n",cnt);
}
return 0;
}

2、LA 3027题目：http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=33982分析：一边路径压缩，一边维护d[i] : 结点i到树根的距离

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;const int maxn=20010;int p[maxn];int d[maxn];int Find(int x){if (p[x] != x){int root=Find(p[x]);d[x] += d[p[x]];return p[x]=root;}else return x;}int main(){int T;scanf("%d",&T);while (T--){int n,u,v;char cmd[9];scanf("%d",&n);for (int i=1;i<=n;i++){p[i]=i;d[i]=0;}while (scanf("%s",cmd) && cmd[0] != 'O'){if (cmd[0] == 'I'){scanf("%d%d",&u,&v);p[u]=v;d[u]=abs(u-v) % 1000;}if (cmd[0] == 'E'){scanf("%d",&u);int t=Find(u);printf("%d\n",d[u]);}}}return 0;}