题目:给出一些询问,[l,r]的和为s,问有多少个是错的
1 //并查集 ,,sum[a]表示a与父亲这条路径上的和 2 #include <iostream> 3 #include <cstdio> 4 #include <cstring> 5 #include <algorithm> 6 7 using namespace std; 8 9 const int maxn = 2e5 + 5; 10 int fa[maxn], sum[maxn]; 11 int n, m, l, r, s; 12 int findFa(int x){ 13 if (x != fa[x]){ 14 int t = fa[x]; 15 fa[x] = findFa(fa[x]); 16 sum[x] += sum[t]; 17 } 18 return fa[x]; 19 } 20 int main(){ 21 while (~scanf("%d%d", &n, &m)){ 22 for (int i = 0; i <= n; ++i){ 23 fa[i] = i; 24 sum[i] = 0; 25 } 26 int ans = 0; 27 while (m--){ 28 scanf("%d%d%d", &l, &r, &s); 29 l --; 30 int pa = findFa(l), pb = findFa(r); 31 if (pa == pb){ 32 if (sum[r] - sum[l] != s) ans++; 33 } 34 else { 35 fa[pb] = pa; 36 sum[pb] = sum[l] - sum[r] + s; 37 } 38 } 39 printf("%d ", ans); 40 } 41 return 0; 42 }