#include <cstdio>
typedef long long ll;
struct AC{
	ll c,y;
}r[11000];
ll n,s;
int main(){
	scanf("%d%d",&n,&s);
	for (int i=1;i<=n;i++)
		scanf("%d%d",&r[i].c,&r[i].y);
	ll ans=0,min=1<<30;
	for (int i=1;i<=n;i++){
		min+=s;
		if (min>r[i].c)
			min=r[i].c;
		ans+=min*r[i].y;
	}
	printf("%lld",ans);
	return 0;
}

• 算法描述 (761) zhouzhendong 2017-02-26 11:49:22
• 总结：贪心法 (0) zhouzhendong 2017-02-26 11:52:19