代码
//
// Created by Genes on 2020/12/9.
//
// 区间和
#include<iostream>
#include<vector>
#include<algorithm>
#define ios \
ios::sync_with_stdio(false); \
cin.tie(nullptr); \
cout.tie(nullptr)
using namespace std;
typedef pair<int, int> pii;
const int N = 3e5 + 10;
int n, m;
int a[N], s[N];
vector<int> alls;//存离散化之后的坐标
vector<pii> add, query;
int find(int x) { // 在离散化后的数组中, 查找一个值为x的下标(第一个>=x), 并将其返回
int l = 0, r = alls.size() - 1;
while (l < r) {
int mid = l + r >> 1;
if (alls[mid] >= x) {
r = mid;
} else {
l = mid + 1;
}
}
return r + 1; //为了方便前缀和, 下标从1开始
}
int main() {
ios;
cin >> n >> m;
for (int i = 0; i < n; i++) {
int x, c;
cin >> x >> c;
add.push_back({x, c});
alls.push_back(x);
}
for (int i = 0; i < m; i++) {
int l, r;
cin >> l >> r;
query.push_back({l, r});
alls.push_back(l);
alls.push_back(r);
}
// 去重
sort(alls.begin(), alls.end());
alls.erase(unique(alls.begin(), alls.end()), alls.end());
for (int i = 0; i < add.size(); i++) {
int x = find(add[i].first);
a[x] += add[i].second;
}
//预处理前缀和
for (int i = 1; i <= alls.size(); i++) {
s[i] = s[i - 1] + a[i];
}
//处理询问
for (int i = 0; i < query.size(); i++) {
int l = find(query[i].first), r = find(query[i].second);
cout << s[r] - s[l - 1] << endl;
}
return 0;
}