首发题解😋

分块可以平衡查询和操作的时间复杂度

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

int main() {
    ios::sync_with_stdio(0), cin.tie(0);
  
    int n;
    cin >> n;
  
    vector<int> a(n);
    for (auto &i : a) {
        cin >> i;
    }
  

    int block_size = sqrt(n);
    int block_count = (n + block_size - 1) / block_size;
    vector<int> lazy(block_count);
  
    for (int i = 0; i < n; ++i) {
        int opt, l, r, c;
        cin >> opt >> l >> r >> c;
  
        l--;
        r--;
  
        if (opt == 0) {
            // 区间[l, r]加上c
            int l_block = l / block_size;
            int r_block = r / block_size;
  
            if (l_block == r_block) {
                // 同一区块内，直接暴力更新
                for (int j = l; j <= r; ++j) {
                    a[j] += c;
                }
            } else {
                // 处理左半部分
                for (int j = l; j < (l_block + 1) * block_size; ++j) {
                    a[j] += c;
                }
                // 处理中间完整的块
                for (int b = l_block + 1; b < r_block; ++b) {
                    lazy[b] += c;
                }
                // 处理右半部分
                for (int j = r_block * block_size; j <= r; ++j) {
                    a[j] += c;
                }
            }
        } else {
            int b = r / block_size;
            cout << a[r] + lazy[b] << '\n';
        }
    }
  
    return 0;
}