pku2393.cpp

这是ACM 方面的资料 是PKU的 北京大学的出来的

#include <stdio.h>

int main()
{
	int n, plus, i;
	__int64 price, min;
	__int64 amount, total;
	scanf("%d %d", &n, &plus);
	scanf("%I64d %I64d", &price, &amount);	
	min = price;
	total = price * amount;
	
	for (i = 1; i < n; i++)
	{
		scanf("%I64d %I64d", &price, &amount);	
		min += plus;
		min = (min < price) ? min : price;
		total += min * amount;
	}
	printf("%I64d\n", total);
	return 0;
}