题目链接

Conscription POJ - 3723

思路

$$ 生成树，注意读题，看清变量代表的是什么。 $$

时间复杂度

$$ O((N + M)log(N + M)) $$

代码

#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

class DSU {
public:
    vector<int> p, r;

    void init(int n) {
        p.resize(n + 10);
        r.resize(n + 10);
        for (int i = 0; i <= n; i++) {
            p[i] = i;
            r[i] = 0;
        }
    }

    int find(int x) {
        if (x == p[x]) {
            return x;
        } else {
            return p[x] = find(p[x]);
        }
    }

    bool unite(int x, int y) {
        x = find(x);
        y = find(y);
        if (x == y) {
            return false;
        }

        if (r[x] < r[y]) {
            p[x] = y;
        } else {
            p[y] = x;
            if (r[x] == r[y]) {
                r[x]++;
            }
        }
        return true;
    }

    bool same(int x, int y) {
        return find(x) == find(y);
    }
};

DSU dsu;
const int MAXN = 5e4 + 10;
int a[MAXN], b[MAXN], c[MAXN], id[MAXN];

bool cmp(int x, int y) {
    return c[x] > c[y];
}
int main() {
    int T;
    scanf("%d", &T);// don't forget &
    while (T--) {
        int n, m, k;
        scanf("%d%d%d", &n, &m, &k);// don't forget &
        dsu.init(n + m);
        for (int i = 1; i <= k; i++) {
            scanf("%d%d%d", &a[i], &b[i], &c[i]);// don't forget &
            id[i] = i;
            b[i] += n;
        }
        sort(id + 1, id + 1 + k, cmp);
        long long w = 0;
        for (int i = 1; i <= k; i++) {
            int x = id[i];
            if (!dsu.same(a[x], b[x])) {
                w += c[x];
                dsu.unite(a[x], b[x]);
            }
        }
        printf("%lld\n", 10000LL * (n + m) - w);
    }
    return 0;
}