Arseniy is already grown-up and independent. His mother decided to leave him alone for m days and left on a vacation. She have prepared a lot of food, left some money and washed all Arseniy's clothes.
Ten minutes before her leave she realized that it would be also useful to prepare instruction of which particular clothes to wear on each of the days she will be absent. Arseniy's family is a bit weird so all the clothes is enumerated. For example, each of Arseniy's n socks is assigned a unique integer from 1 to n. Thus, the only thing his mother had to do was to write down two integers li and ri for each of the days — the indices of socks to wear on the day i (obviously, li stands for the left foot and ri for the right). Each sock is painted in one of kcolors.
When mother already left Arseniy noticed that according to instruction he would wear the socks of different colors on some days. Of course, that is a terrible mistake cause by a rush. Arseniy is a smart boy, and, by some magical coincidence, he posses k jars with the paint — one for each of k colors.
Arseniy wants to repaint some of the socks in such a way, that for each of m days he can follow the mother's instructions and wear the socks of the same color. As he is going to be very busy these days he will have no time to change the colors of any socks so he has to finalize the colors now.
The new computer game Bota-3 was just realised and Arseniy can't wait to play it. What is the minimum number of socks that need their color to be changed in order to make it possible to follow mother's instructions and wear the socks of the same color during each of mdays.
The first line of input contains three integers n, m and k (2 ≤ n ≤ 200 000, 0 ≤ m ≤ 200 000, 1 ≤ k ≤ 200 000) — the number of socks, the number of days and the number of available colors respectively.
The second line contain n integers c1, c2, ..., cn (1 ≤ ci ≤ k) — current colors of Arseniy's socks.
Each of the following m lines contains two integers li and ri (1 ≤ li, ri ≤ n, li ≠ ri) — indices of socks which Arseniy should wear during the i-th day.
Print one integer — the minimum number of socks that should have their colors changed in order to be able to obey the instructions and not make people laugh from watching the socks of different colors.
3 2 3 1 2 3 1 2 2 3
2
3 2 2 1 1 2 1 2 2 1
0
In the first sample, Arseniy can repaint the first and the third socks to the second color.
In the second sample, there is no need to change any colors.
题意:有n个袜子,每天穿指定的两个袜子,如果他们不同颜色要把他们涂成相同颜色,问最少需要涂几次。
思路:并查集,把有关联的袜子放在一起,把有关联的全部涂成相同颜色最多的那个就是答案。即假设答案为ans,某集合里袜子总数为m,集合里袜子颜色相同最多的是n,则有ans+=m-n。下面给代码:
#include<cstdio>
#include<cstring>
#include<vector>
#include<queue>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<bitset>
#include<map>
#include <utility>
using namespace std;
#define maxn 200005
#define inf 0x3f3f3f3f
typedef long long LL;
const int mod = 1e9 + 7;
int a[maxn], vis[maxn], num[maxn], maxnum[maxn];
map<int, int>mm[maxn];
int find(int x){
while (vis[x]){
x = vis[x];
}
return x;
}
void mul(int x, int y){
int xx = find(x);
int yy = find(y);
if (xx == yy)
return;
if (num[xx] >= num[yy]){
vis[yy] = xx;
num[xx] += num[yy];
}
else{
vis[xx] = yy;
num[yy] += num[xx];
}
}
int main(){
int n, m, k;
while (~scanf("%d%d%d", &n, &m, &k)){
for (int i = 1; i <= n; i++){
scanf("%d", &a[i]);
vis[i] = 0;
maxnum[i] = 0;
num[i] = 1;
}
int ans = 0;
for (int i = 0; i < m; i++){
int x, y;
scanf("%d%d", &x, &y);
mul(x, y);
}
for (int i = 1; i <= n; i++){
int now = find(i);
mm[now][a[i]]++;
int t = mm[now][a[i]];
if (t>maxnum[now]){
maxnum[now] = t;
}
}
for (int i = 1; i <= n; i++){
int now = find(i);
if (num[now]){
ans += num[now] - maxnum[now];
num[now] = 0;
}
}
printf("%d\n", ans);
}
}
本文介绍了一种通过并查集解决袜子颜色调整问题的算法,旨在确保每天穿着颜色一致的袜子,通过将相关联的袜子合并并统一颜色,实现最小化颜色调整次数。
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