代码：

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N = 2e5 + 10;
int n, m, w[N], v[N], l[N], r[N];
LL s, sw[N], sv[N], ans;//前缀和 
int x, y;//二分范围 
int main(){
	cin >> n >> m >> s;
	ans = s;//差值初始化 
	for(int i = 1; i <= n; i ++){
		cin >> w[i] >> v[i];
		y =  max(y, w[i]);
	}
	x = 0, y = y + 1;
	for(int i = 1; i <= m;i ++){
		cin >> l[i] >> r[i];
 	}
 	while(x < y){
 		memset(sw, 0, sizeof(sw));
		memset(sv, 0, sizeof(sv));
		int W = (x + y) >> 1;
		for(int i = 1; i <= n; i ++){
			if(w[i] >= W){
				sw[i] = sw[i - 1] + 1;
				sv[i] = sv[i - 1] + v[i];
			}else{
				sw[i] = sw[i - 1];
				sv[i] = sv[i - 1];
			}
		}
		LL sum = 0;
		for(int i = 1; i <= m; i ++){
			sum += (LL)(sw[r[i]] - sw[l[i] - 1]) * (sv[r[i]] - sv[l[i] - 1]);
		}
		if(sum == s){
			ans = 0;
			break;
		}else{
			ans = min(ans, abs(s - sum));
			if(sum > s){
				//W小了
				x = W + 1; 
			}else{
				y = W;
			}
		} 
	}
	cout << ans;
	return 0;
}

1. 在代码中 将 $x$ 初始设为 $1$ 和 $0$ 有什么区别？
2. 二分写 while(x<y), x = mid + 1, y = mid 与 while(x<=y), x = mid + 1, y = mid - 1有什么区别？