@[隋乐珉](/user/183990) 帮您改了一下建树，现在建树好了，但是您的修改函数还是有问题
```cpp
void build(int num, int l, int r) {
t[num].l = l;
t[num].r = r;
t[num].tagc = 1;
t[num].tagj = 0;
if (l == r) {
assert(p != 0);
t[num].sum = a[l] % p;
return;
}
//cout<<"build_bug"<<" ";
int mid = (l + r) >> 1;
// cout << num << " " << l << " "
// << " " << r << " " << mid << endl;
build(num * 2, l, mid);
// cout << "ok";
build(num * 2 + 1, mid + 1, r);
t[num].sum = t[num << 1].sum + t[num << 1 | 1].sum;
t[num].sum %= p;
}
```
by answerend42 @ 2020-12-01 00:17:07