[ACM]数列分块

数列分块

1____* 板子题 *

#include <bits/stdc++.h>
using namespace std;

const int N = 5e4 + 10;
int id[N], len;
int a[N], b[N], s[N];

void add(int l, int r, int c) {
    int sid = id[l], eid = id[r];

    if (sid == eid) {
        for (int i = l ; i <= r; i++)
            a[i] += c, s[ sid ] += c;

        return ;
    }

    for (int i = l ; id[i] == sid ; i++)
        a[i] += c, s[ sid ] += c;

    for (int i = sid + 1; i < eid ; i ++)
        b[i] += c, s[ i ] += c * len;

    for (int i = r ; id[i] == eid ; i--)
        a[i] += c, s[ eid ] += c;
}

int query(int x) {
    return a[x] + b[ id[x] ];
}


int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    int n;
    cin >> n;
    len = sqrt(n);

    for (int i = 1 ; i <= n ; i++) {
        cin >> a[i];
        id[i] = (i - 1) / len + 1;
        s[ id[i] ] += a[i];
    }

    for (int i = 0 ; i < n ; i++) {
        int op, l, r, c;
        cin >> op >> l >> r >> c;

        if (op == 0) {
            add(l, r, c);
        } else {
            cout << query(r) << endl;
        }
    }

    return 0;
}