893CRumor

并查集

用并查集模板，把属于同一个集合归在一起，然后集合中取最小的集合，也就是花费黄金最少的集合。

                                C. Rumor                                time limit per test2 seconds                                memory limit per test256 megabytes                                inputstandard input                                outputstandard output                                Vova promised himself that he would never play computer games... But recently Firestorm — a well-known game developing company — published their newest game, World of Farcraft, and it became really popular. Of course, Vova started playing it.

Now he tries to solve a quest. The task is to come to a settlement named Overcity and spread a rumor in it.

Vova knows that there arencharacters in Overcity. Some characters are friends to each other, and they share information they got. Also Vova knows that he can bribe each character so he or she starts spreading the rumor;i-th character wantscigold in exchange for spreading the rumor. When a character hears the rumor, he tells it to all his friends, and they start spreading the rumor to their friends (for free), and so on.

The quest is finished when allncharacters know the rumor. What is the minimum amount of gold Vova needs to spend in order to finish the quest?

Take a look at the notes if you think you haven’t understood the problem completely.

Input
The first line contains two integer numbersnandm(1 ≤n≤ 105, 0 ≤m≤ 105) — the number of characters in Overcity and the number of pairs of friends.

The second line containsninteger numbersci(0 ≤ci≤ 109) — the amount of goldi-th character asks to start spreading the rumor.

Thenmlines follow, each containing a pair of numbers (xi,yi) which represent that charactersxiandyiare friends (1 ≤xi,yi≤n,xi≠yi). It is guaranteed that each pair is listed at most once.

Output
Print one number — the minimum amount of gold Vova has to spend in order to finish the quest.

Examples
input
5 2
2 5 3 4 8
1 4
4 5
output
10
input
10 0
1 2 3 4 5 6 7 8 9 10
output
55
input
10 5
1 6 2 7 3 8 4 9 5 10
1 2
3 4
5 6
7 8
9 10
output
15
Note
In the first example the best decision is to bribe the first character (he will spread the rumor to fourth character, and the fourth one will spread it to fifth). Also Vova has to bribe the second and the third characters, so they know the rumor.

In the second example Vova has to bribe everyone.

In the third example the optimal decision is to bribe the first, the third, the fifth, the seventh and the ninth characters.

#include<cstdio>#include<iostream>#include<algorithm>using namespace std;const int N=1e5+10;int m,n;long long ans;int fa[N],a[N],x,y;int find(int x){    if(x!=fa[x])        fa[x]=find(fa[x]);    return fa[x];}void meger(int x,int y){    int xx=find(x);    int yy=find(y);    if(xx!=yy)    {        fa[xx]=yy;        a[yy]=min(a[yy],a[xx]);    }}int main(){    while(cin>>n>>m)    {        ans=0;        for(int i=1; i<=n; i++)            fa[i]=i;        for(int i=1; i<=n; i++)            cin>>a[i];        for(int i=0; i<m; i++)        {            cin>>x>>y;            meger(x,y);        }        for(int i=1;i<=n;i++)            if(i==find(i))            ans+=a[i];        cout<<ans<<endl;    }    return 0;}