【图+并查集】Total Eclipse

Total Eclipse 代码如下
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define LL long long
#define UIT unsigned int
#define DB double
#define PII pair
#define MKPR(a, b) make_pair(a, b)
#define MMST(a) memset(a, 0, sizeof(a))
#define PB push_back
#define FOR(i, beg, ed, s) for (int i = beg; i < ed; i += s)
#define FORE(i, beg, ed, s) for (int i = beg; i <= ed; i += s)
#define LOOP while (true)
#define IN scanf
#define OUT printf
using namespace std;

vector f;
vector a;
vector> mp;
vector vis;

//比较函数
bool cmp(const PII& a, const PII& b) {
    if (a.first == b.first) {
        return a.second < b.second;
    }
    return a.first > b.first;  //只写这一句也可
}

//并查集标准函数
int find(int x) {
    int r = x;
    while (r != f[r]) {
        r = f[r];
    }

    int t = x;
    int tmp = 0;
    while (t != tmp) {
        tmp = f[t];
        f[t] = r;
        t = tmp;
    }
    return r;
}

void uni_set(int x, int y) {
    int xx = find(x);
    int yy = find(y);
    if (xx != yy) {
        f[xx] = yy;
    }
}

void solve() {
    int t = 0, m = 0, n = 0;
    int x = 0, y = 0;
    int cnt = 0;
    LL ans = 0;
    IN("%d", &t);
    while (t--) {
        IN("%d%d", &n, &m);
        f.resize(n + 1);
        mp.resize(n + 1);
        a.resize(n + 1);
        vis.resize(n + 1);
        FORE(i, 1, n, 1) {
            IN("%d", &a[i].first);
            a[i].second = i;
            mp[i].clear();
            f[i] = i;
            vis[i] = false;
        }
        //排序，按权值从大到小
        sort(a.begin() + 1, a.end(), cmp);
        a.PB(MKPR(0, 0));
        ans = 0;
        cnt = 0;

        //建图，邻接表
        while (m--) {
            IN("%d%d", &x, &y);
            mp[x].PB(y);
            mp[y].PB(x);
        }

        FORE(i, 1, n, 1) {
            cnt++;  //连通块个数先加一，即假设当前点是一个独立点
            vis[a[i].second] = true;  //已访问
            //遍历该点的邻接点
            for (auto it : mp[a[i].second]) {
                if (vis[it]) {
                    //若邻接点在当前点之前被访问过(两个点相连)
                    if (find(it) != find(a[i].second)) {
                        cnt--;  //那么连通块个数减一
                        //加入并查集
                        uni_set(it, a[i].second);
                    }
                }
            }
            //更新答案
            ans += 1LL * cnt * (a[i].first - a[i + 1].first);
        }
        OUT("%lldn", ans);
    }
}

int main(void) {
    solve();
    return 0;
}
【图+并查集】Total Eclipse

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