对于样例，在i = 3时找到的j就开始错了

#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 3e5 + 20;
ll n, s, C[N], T[N], f[N];
ll h = 1, t = 1;
struct node{
	ll x, y, id;
}q[N];
double slope(double x, double y) {
	return y / (x == 0 ? 1e-9 : x);
}
int main (){
	scanf("%lld%lld", &n, &s);
	for(int i = 1; i <= n; i++) {
		ll t, c;
		scanf("%lld%lld", &t, &c);
		T[i] = T[i-1] + t;
		C[i] = C[i-1] + c;
	}
	
	q[1]= (node){0,  0, 0};
	for(int i = 1; i <= n; i++) {
        ll l = 1, r = t;
        while(l < r) {
        	ll mid = (l + r ) >> 1;
        	if(mid == t) {
        		l = t;
			    break;
			}
        	if(slope(1.0 * q[mid + 1].x - q[mid].x, 1.0 * q[mid + 1].y - q[mid].y) <= 1.0 * (T[i] - s)) l = mid + 1;
        	else r = mid;
		}
		if(l > t) l = t;
		ll j = q[l].id;
		f[i] = f[j] + T[i] * (C[i] - C[j]) + s * (C[n] - C[j]);
		ll x = C[i], y = f[i];
		while(h < t && slope(1.0 * q[t].x - q[t-1].x, 1.0 * q[t].y - q[t-1].y) >= slope(1.0 * x - q[t].x, 1.0 * y - q[t].y)) t--;
		q[++t] = (node){x, y, i};
		cout << j << endl;
	}
	printf("%lld", f[n]);
	
	return 0;
}