D - How Many Answers Are Wrong——种类并查集

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 2e5 + 4;

int n, m, f
, sum
;/*sum数组为后缀和数组:sum[x] = [ x, f[x] ]*/

void Init();
int get_f(int x);

int main(){
int ans, i, l, r, w;
while(~scanf("%d %d", &n, &m)){
ans = 0;
Init();
for(i = 1; i <= m; i++){
scanf("%d %d %d", &l, &r, &w);
l -= 1;

int t1 = get_f(l);
int t2 = get_f(r);

if(t1 == t2){
if(sum[l]-sum[r] != w)
ans++;
}
else if(t1 < t2){
f[t1] = t2;
sum[t1] = sum[r] + w - sum[l];/*sum[t1] = [ t1, f[t1] ] = [t1, t2] = sum[r] + w - sum[l]*/
}
else if(t1 > t2){
f[t2] = t1;
sum[t2] = sum[l] - w - sum[r];/*sum[t2] = [ t2, f[t2] ] = [t2, t1] = sum[l] - w - sum[r]*/
}
}
printf("%d\n", ans);
}
return 0;
}
void Init(){
for(int i = 0; i <= n; i++){
f[i] = i;
sum[i] = 0;
}
}
int get_f(int x){
if(f[x] == x)
return f[x];
else {
int t = f[x];
f[x] = get_f(f[x]);
sum[x] += sum[t];
return f[x];
}
}