CodeForces 731C Socks

http://codeforces.com/problemset/problem/731/C

并查集+贪心 将要求颜色相同的袜子序号放入一个集合中

贪心：然后统计这个集合中出现次数最多但颜色 可以得到这个集合要repain的次数

代码有难度

统计集合数

int tot;//总的集合数

for (int i = 1; i <= n; i++)

　　if(par[i] == i)

{

　　rec[tot++] = i;//记录根节点

} 

//统计每个集合红颜色的个数

map<int, int> clmp;

vector<int> G[MAXN];

for(int i = 1; i <= n; i++)

{

　　G[par[i]].push_back(color[i]);

}

int ans = 0;

for(int i = 0; i < tot; i++)//统计颜色情况

{

　　clmp.clear();

　　for (int j = 0; j < v[rec[i]].size(); j++)

　　clmp[v[rec[i]][j]]++;

}

#include <bits/stdc++.h>
#define MAXN 200007
using namespace std;

int par[MAXN];

int find(int x)
{
    if (par[x] == x) return x;
    else return par[x] = find(par[x]);
}
bool same(int x, int y)
{
    int px, py;
    px = find(x);
    py = find(y);
    return px == py;
}
void unite(int x, int y)
{
    int px = find(x);
    int py = find(y);
    par[px] = py;
}
int color[MAXN];
int rec[MAXN];
vector<int> v[MAXN];
map<int,int> clmap;
int main()
{
    int day, paint, socks, ans = 0;
    scanf("%d%d%d", &socks, &day, &paint);
    for (int i =  0;  i <= socks; i++) par[i] = i;
    for (int i = 1; i <= socks; i++)
    {
        scanf("%d", &color[i]);
    }
    for (int i = 0; i < day; i++)
    {
        int l, r;
        scanf("%d%d", &l, &r);
        unite(l, r);
    }
    int tot = 0;
    for (int i = 1; i <= socks; i++)
    {
        if (i == find(i))
        {
            rec[tot++] = i;
        }
    }
    for (int i = 1; i <= socks; i++)
    {
        v[par[i]].push_back(color[i]);
    }
    for (int i = 0; i < tot; i++)
    {
        clmap.clear();
        for(int j = 0; j < v[rec[i]].size(); j++)
        {
            clmap[v[rec[i]][j]]++;
        }
        map<int,int> :: iterator it;
        int maxn = 0;
        for (it = clmap.begin(); it != clmap.end(); it++)
        {
            maxn = max(maxn, (*it).second);
        }
        ans += v[rec[i]].size() - maxn;
    }
    cout << ans << endl;
}