51 lines
1.0 KiB
C++
51 lines
1.0 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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const int N = 100005;
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int p[N];
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int score[N];
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int find(int x) {
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if (x != p[x]) {
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int t = p[x];
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p[x] = find(p[x]);
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score[x] += score[t];
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}
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return p[x];
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}
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//https://blog.csdn.net/yjr3426619/article/details/82315133
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int main() {
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//输入+输出重定向
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freopen("../AcWing/N5/HihoCoder1515.txt", "r", stdin);
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int n, m, q;
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scanf("%d%d%d", &n, &m, &q);
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for (int i = 1; i <= n; i++) {
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p[i] = i;
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}
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while (m--) {
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int x, y, s;
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scanf("%d%d%d", &x, &y, &s);
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int px = find(x);
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int py = find(y);
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if (px != py) {
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p[px] = py;
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score[px] = -score[x] + score[y] + s;
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}
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}
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while (q--) {
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int x, y;
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scanf("%d%d", &x, &y);
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if (find(x) != find(y)) {
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printf("-1\n");
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} else {
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printf("%d\n", score[x] - score[y]);
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}
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}
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//关闭文件
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fclose(stdin);
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return 0;
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} |