poj2393 Yogurt factory

思路：

贪心。

实现：

 #include <iostream>
 #include <cstdio>
 #include <algorithm>
 using namespace std;
 typedef long long ll;
 struct node
 {
     ll c, y;
 };
 node a[];
 ll n, s;

 int main()
 {
     cin >> n >> s;
     for (ll i = ; i < n; i++)
     {
         scanf("%d %d", &a[i].c, &a[i].y);
     }
     ll sum = a[].y * a[].c;
     for (ll i = ; i < n; i++)
     {
         sum += min(a[i].c * a[i].y, (a[i - ].c + s)* a[i].y);
     }
     cout << sum << endl;
     return ;
 }