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最新推荐文章于 2020-09-19 14:00:42 发布

Little_boy_z

最新推荐文章于 2020-09-19 14:00:42 发布

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侦探Conan面对Kiddo提出的难题：判断一个数组是否为魔法数组，即通过删除k个元素后剩余部分是否能形成非递增或非递减序列。此问题类似于寻找最长递增子序列。

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Problem Description

One day, Kaitou Kiddo had stolen a priceless diamond ring. But detective Conan blocked Kiddo's path to escape from the museum. But Kiddo didn't want to give it back. So, Kiddo asked Conan a question. If Conan could give a right answer, Kiddo would return the ring to the museum.
Kiddo: "I have an array

A and a number

k, if you can choose exactly

k elements from

A and erase them, then the remaining array is in non-increasing order or non-decreasing order, we say

A is a magic array. Now I want you to tell me whether

A is a magic array. " Conan: "emmmmm..." Now, Conan seems to be in trouble, can you help him?

Input

The first line contains an integer T indicating the total number of test cases. Each test case starts with two integers

n and

k in one line, then one line with

n integers:

A1,A2…An.

1≤T≤20

1≤n≤105

0≤k≤n

1≤Ai≤105

Output

For each test case, please output "A is a magic array." if it is a magic array. Otherwise, output "A is not a magic array." (without quotes).

Sample Input

3
4 1
1 4 3 7
5 2
4 1 3 1 2
6 1
1 4 3 5 4 6

Sample Output

A is a magic array.
A is a magic array.
A is not a magic array.

类似于最长递增子序列

正方来一次，反向来一次。

#include <bits/stdc++.h>
using namespace std;

const int MAXN = 1e5+10;
int a[MAXN];
int b[MAXN];
int t[MAXN];
int len1,len2;

int main()
{
    int T,n,k;
    scanf("%d",&T);
    while(T--)
    {
        memset(b,0,sizeof(b));
        scanf("%d %d",&n,&k);
        for(int i = 0; i < n; ++i)
        {
            scanf("%d",&a[i]);
            t[n-i-1] = a[i];
        }

        b[1] = a[0];
        int len = 1,j;
        for(int i = 1; i < n; ++i)
        {
            if(a[i] >= b[len])
                b[++len] = a[i];
            else
            {
                j = lower_bound(b+1,b+1+len,a[i])-b;
                b[j] = a[i];
            }
        }
        len1 = n-len;

        memset(b,0,sizeof(b));
        b[1] = t[0];
        len = 1;
        for(int i = 1; i < n; ++i)
        {
            if(t[i] >= b[len])
                b[++len] = t[i];
            else
            {
                j = lower_bound(b+1,b+1+len,t[i])-b;
                b[j] = t[i];
            }
        }
        len2 = n-len;
        if(k >= len1 || k >= len2)
            printf("A is a magic array.\n");
        else
            printf("A is not a magic array.\n");
    }
    return 0;
}