num[i]代表i到根节点的值
这道题一开始竟然以为是线段树= =！后来发现线段树无法进行子区间的维护
#include<cstdio>#include<cstring>#include<algorithm>using namespace std;const int maxn = 222222;int fa[maxn],num[maxn];int find_father(int u){if(fa[u] == u)return fa[u];else{int temp = fa[u];fa[u] = find_father(fa[u]);num[u] += num[temp];return fa[u];}}int main(){int n,m;while(scanf("%d%d",&n,&m) != EOF){memset(num,0,sizeof(num));int cnt = 0;for(int i = 0; i <= n; i++) fa[i] = i;for(int i = 0; i < m; i++){int x,y,z;scanf("%d%d%d",&x,&y,&z);x –;int l = find_father(x),r = find_father(y);if(l == r){int e = num[y] – num[x];if(e != z){cnt ++;}}else{fa[r] = l;num[r] = z + num[x] – num[y];}}printf("%d\n",cnt);}return 0;}
，这一次是一个告别，或者一个永远的告别，
