CF797E. Array Queries

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原文链接：http://www.cnblogs.com/-xiangyang/p/9441564.html

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#数据结构与算法

a is an array of n positive integers, all of which are not greater than n.

You have to process q queries to this array. Each query is represented by two numbers p and k. Several operations are performed in each query; each operation changes p to p + ap + k. There operations are applied until p becomes greater than n. The answer to the query is the number of performed operations.

Input

The first line contains one integer n (1 ≤ n ≤ 100000).

The second line contains n integers — elements of a (1 ≤ ai ≤ n for each i from 1 to n).

The third line containts one integer q (1 ≤ q ≤ 100000).

Then q lines follow. Each line contains the values of p and k for corresponding query (1 ≤ p, k ≤ n).

Output

Print q integers, ith integer must be equal to the answer to ith query.

Example

input

output

2
1
1

Consider first example:

In first query after first operation p = 3, after second operation p = 5.

In next two queries p is greater than n after the first operation.

题意：

给你q次查询，每次会有两个数字p，k,问每次使p=p+a[p]+k,总共需要多少次会使p>n

题解:

存粹暴力必然超时，因此需要打个表，

#include<bits/stdc++.h>
using namespace std;
const int MAXN=1e5+10;
const int INF=-0x3f3f3f3f;
int a[MAXN];
int dp[MAXN][510];
int main()
{
	int n;
	scanf("%d",&n);
    for (int i = 1; i <=n ; ++i) {
        scanf("%d",&a[i]);
    }
    for(int i=n;i>=1;i--) {//表示为p,由大->小，我们需要变化的次数增加
        for (int j = 1; j <=500; ++j) {//表示为k的大小
            if(i+a[i]+j>n) dp[i][j]=1;
            else
            dp[i][j]=dp[i+a[i]+j][j]+1;
        }
    }
    int ans=0;
    int m;
    scanf("%d",&m);
    int p,k;
    while(m--)
    {
        ans=0;
        scanf("%d%d",&p,&k);
        if(k>400)
        {
            while(p<=n)
            {
                p=p+a[p]+k;
                ans++;
            }
            printf("%d\n",ans);
        }
        else
            printf("%d\n",dp[p][k]);
    }
	return 0;
 }

转载于:https://www.cnblogs.com/-xiangyang/p/9441564.html