题目:
描述:
题解:
代码:
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxn = 2e5 + 5;
int fa[maxn], sum[maxn];
int find(int x)
{
if(fa[x] == -1) return x;
int tmp = find(fa[x]);
sum[x] += sum[fa[x]];
return fa[x] = tmp;
}
int main()
{
int n, m, ans, l, r, s;
while(~scanf("%d%d", &n, &m))
{
memset(fa, -1, sizeof(fa));
memset(sum, 0, sizeof(sum));
ans = 0;
while(m--)
{
scanf("%d%d%d", &l, &r, &s); l--;
int ll = find(l), rr = find(r);
if(ll == rr)
{
if(sum[r] - sum[l] != s) ans++;
}
else
{
fa[rr] = ll;
sum[rr] = -sum[r] + s + sum[l];
}
}
printf("%d\n", ans);
}
return 0;
}