HDU-3038-How Many Answers Are Wrong
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链接:https://vjudge.net/problem/HDU-3038#author=0
题意:
给出N和M
有M次记录,以l,r,v给出,表示l-r区间和为v问,有多少是错误的答案。
思路:
带权并查集。
sum[i] 表示i到F[i]的和。
代码:
#include <iostream> #include <memory.h> #include <string> #include <istream> #include <sstream> #include <vector> #include <stack> #include <algorithm> #include <map> #include <queue> #include <math.h> using namespace std; const int MAXN = 500086; int Father[MAXN]; int Sum[MAXN]; int Get_F(int x) { if (x == Father[x]) return x; int tmp = Father[x]; Father[x] = Get_F(Father[x]); Sum[x] += Sum[tmp]; return Father[x]; } int main() { int n,m; //while (scanf("%d%d",&n,&m)) while (cin >> n >> m) { for (int i = 0; i <= n; i++) Father[i] = i; memset(Sum, 0, sizeof(Sum)); int l, r, v; int cnt = 0; for (int i = 1; i <= m; i++) { scanf("%d%d%d", &l, &r, &v); l--; int tl = Get_F(l); int tr = Get_F(r); if (tl != tr) { Father[tl] = tr; Sum[tl] = Sum[r] + v - Sum[l]; } else { if (Sum[l] - Sum[r] != v) cnt++; } } printf("%d ", cnt); } return 0; }
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