# include <stdio.h> # include <string.h> # include <algorithm> using namespace std; int main() { int i,n,s; __int64 sum ; int cost[10010],num[10010]; while(~scanf("%d%d",&n,&s)) { for(i=0;i<n;i++) scanf("%d%d",&cost[i],&num[i]); for(i=0;i<n;i++) { if(i==0) sum=cost[i]*num[i]; else { if(cost[i]>cost[i-1]+s) { sum+=(cost[i-1]+s)*num[i]; cost[i]=cost[i-1]+s;//更新最省价格 } else { sum+=cost[i]*num[i]; } } } printf("%I64d\n",sum); } return 0; }
时间: 2024-11-10 07:34:42