2019-2020 ICPC North-Western Russia Regional Contest H題(High Load Database)

High Load Database
補題思路來源

#include<bits/stdc++.h>
using namespace std;
 
const int N=1e6+5;
int n,ans[N],sum[N],Sz[N],mx; 
 
int solve(int k){
	if(k<mx)
		return -1;
	if(ans[k])
		return ans[k];
	int i=0,res=0;
	while(i<n){
		res=min(res+k,N); 
		i=Sz[res];
		res=sum[i];
		ans[k]++;
	}
	return ans[k];
}
 
int main(){
	int T,v,k;
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		scanf("%d",&v);
		mx=max(v,mx);
		sum[i]=sum[i-1]+v;
		for(int j=sum[i-1];j<sum[i];j++)//因爲題目說明這個sum[n]小於1e6所以這個循環不會超時 
			Sz[j]=i-1;//Sz[j]表示容積爲j的揹包最多裝下前面連續幾個物品 
	}
	for(int i=sum[n];i<=N;i++)
		Sz[i]=n; 
	scanf("%d",&T);
	while(T--){
		scanf("%d",&k);	
		if(solve(k)==-1)puts("Impossible");	
		else printf("%d\n",solve(k));
	}
}