16. AtCoder-AtCoder Express 2

题目链接：AtCoder Express 2

一维的情况不好直接做，可以将其转化到二维中，这样就相当于矩形内数点了，二维前缀和就可以解决。

#include 
using namespace std;
#define endl '\n'
const int maxn = 500 + 5;
int s[maxn][maxn];
void solve() {
	int n, m, q;
	cin >> n >> m >> q;
	for (int i = 1, x, y; i <= m; ++i) {
		cin >> x >> y;
		s[x][y]++;
	}
	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= n; ++j)
			s[i][j] += s[i - 1][j] + s[i][j - 1] - s[i - 1][j - 1];
	}
	for (int i = 1, x, y; i <= q; ++i) {
		cin >> x >> y;
		cout << s[y][y] - s[x - 1][y] - s[y][x - 1] + s[x - 1][x - 1] << endl;
	}
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
    // cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}