hdu 3038 How Many Answers Are Wrong(并查集)

来源：互联网发布：windows route delete 编辑：程序博客网时间：2024/05/22 13:34

题目链接：hdu 3038 How Many Answers Are Wrong

题目大意：略。

解题思路：并查集水题。

#include <cstdio>#include <cstring>#include <iostream>using namespace std;typedef long long ll;const int N = 200005;//const ll UFmod = 0x3f3f3f3f3f;struct UFset {    int root;    int parent;    ll value;}U[N];int UFfind(int x) {    if (U[x].root == 0) {        int tmp = U[x].parent;        U[x].parent = UFfind(U[x].parent);//        U[x].value = (U[x].value + U[tmp].value) % UFmod;        U[x].value = U[x].value + U[tmp].value;        return U[x].parent;    } else        return x;}void UFunion(int x, int y, int p, int q, ll type) {    U[p].parent += U[q].parent;    U[q].parent = p;    U[q].root = 0;//    U[q].value = (U[x].value + type + UFmod - U[y].value) % UFmod;    U[q].value = (U[x].value + type - U[y].value);}void UFinit (int n) {    for (int i = 0; i <= n; i++) {        U[i].parent = 1;        U[i].value = 0;        U[i].root = 1;    }}int n, m;int main () {    while (scanf("%d%d", &n, &m) == 2) {        UFinit(n);        int a, b, ans = 0;        ll c;        for (int i = 0; i < m; i++) {            scanf("%d%d", &a, &b);            cin >> c;            a--;            int p = UFfind(a), q = UFfind(b);            if (p == q) {                if (U[a].value + c != U[b].value)                    ans++;            } else {                UFunion(a, b, p, q, c);            }        }        printf("%d\n", ans);    }    return 0;}

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