一维前缀和模板

#include <iostream>using namespace std;
const int N = 1e5 + 10;
int a[N];int main(){int n, m;cin >> n >> m;for (int i = 1; i <= n; i ++){cin >> a[i];a[i] = a[i - 1] + a[i];} // 计算输出while(m --){int l, r;cin >> l >> r;cout << a[r] - a[l - 1] << endl;}return 0;
}

二维前缀和模板

#include <iostream>using namespace std;const int N = 1010;
int a[N][N];int main(){int n, m, q;cin >> n >> m >> q;// 读入矩阵for(int i = 1; i <= n; i ++){for (int j = 1; j <= m; j ++){cin >> a[i][j];a[i][j] = a[i][j-1] + a[i-1][j] - a[i-1][j-1] + a[i][j];}}// 输出子矩阵和while(q --){int x1, y1, x2, y2;cin >> x1 >> y1 >> x2 >> y2;cout << a[x2][y2] - a[x2][y1-1] - a[x1-1][y2] + a[x1-1][y1-1] << endl;}return 0;
}