ICPC2017沈阳网赛1004&&HDU6197 （LIS

最新推荐文章于 2017-09-20 08:08:20 发布

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最新推荐文章于 2017-09-20 08:08:20 发布

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本文链接：https://blog.youkuaiyun.com/wang2332/article/details/77941478

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本文介绍了一个有趣的问题：如何判断一个数组是否为魔法数组。通过给定的元素数量和允许更改的元素数量，我们需要确定该数组经过修改后是否能变为非递增或非递减排列。文章提供了详细的算法实现步骤，并附带了完整的代码示例。

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array array array

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.

题意

就是问你数组内最长上升或者下降子序列+k与n的关系

AC代码

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

const int MAXN = 1e6+10;
int arr[MAXN], brr[MAXN];
int n, k;
int Search(int num, int low, int high)
{
    int mid;
    while(low <= high) {
        mid = (low+high) / 2;
        if(num >= brr[mid])
            low = mid+1;
        else
            high = mid-1;
    }
    return low;
}
int Dp()
{
    int len, pos;
    brr[1] = arr[1];
    len = 1;
    for(int i = 2;i <= n; i++) {
        if(arr[i] >= brr[len]) {
            len ++; brr[len] = arr[i];
        }
        else {
            pos = Search(arr[i], 1, len); brr[pos] = arr[i];
        }
    }
    return len;
}
int Dp1()
{
    int len, pos;
    brr[1] = arr[1];
    len = 1;
    for(int i = 2;i <= n; i++) {
        if(arr[i] <= brr[len]) {
            len ++; brr[len] = arr[i];
        }
        else {
            pos = Search(arr[i], 1, len); brr[pos] = arr[i];
        }
    }
    return len;
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--) {
        scanf("%d%d",&n,&k);
        for(int i = 1; i <= n; i++) scanf("%d",&arr[i]);
        int zz = Dp()+k; int kk = Dp1()+k;
        if(zz>=n || kk >+ n) puts("A is a magic array.");
        else puts("A is not a magic array.");
    }
return 0;
}