HDU 3038 How Many Answers Are Wrong

#include <cstdio>
using namespace std;

#define N 200001

int fa[N], sum[N], ans;

void init(int n) {
    ans = 0;
    for (int i = 0; i <= n; i++) {
        fa[i] = i;
        sum[i] = 0;
    }
}

int findfa(int n) {
    if (n == fa[n]) {
        return n;
    }
    int t = findfa(fa[n]);
    sum[n] += sum[fa[n]];
    return fa[n] = t;
}

bool unite(int l, int r, int s) {
    int x = findfa(l), y = findfa(r);
    if (x == y) {
        return (sum[l] - sum[r] != s);
    }
    fa[x] = y;
    sum[x] = sum[r] - sum[l] + s;
    return 0;
}

int main() {
    int n, q, l, r, s;
    while (~scanf("%d%d", &n, &q)) {
        init(n);
        for (int i = 0; i < q; i++) {
            scanf("%d%d%d", &l, &r, &s);
            ans += unite(l - 1, r, s);
        }
        printf("%d\n", ans);
    }
    return 0;
}