array array array
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 1613 Accepted Submission(s): 798
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.
Source
2017 ACM/ICPC Asia Regional Shenyang Online
nlgn 求最长上升子序列
dp[k] 为长度为k时最小的 a[i]值, 如果a[i] >= dp[j], 说明dp[j+1] = a[i]; 否则 二分查找dp{1-j} 中a[i] 所处的位置,并用a[i]取代。
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 100;
int T;
int n,k;
int dp[maxn],a[maxn];
int main()
{
scanf("%d",&T);
while(T--)
{
scanf("%d%d",&n,&k);
for(int i = 0; i < n; i++)
scanf("%d",&a[i]);
dp[0] = -1;
int j = 0;
for(int i = 0; i < n; i++)
if(a[i] >= dp[j]) dp[++j] = a[i];
else {
int idx = lower_bound(dp+1,dp+j+1,a[i]) - dp;
dp[idx] = a[i];
}
if(k >= n-j) {printf("A is a magic array.\n");continue;}
dp[0] = -1;j = 0;
for(int i = 0; i < n/2; i++) swap(a[i],a[n-1-i]);
for(int i = 0; i < n; i++)
if(a[i] >= dp[j]) dp[++j] = a[i];
else {
int idx = lower_bound(dp+1,dp+j+1,a[i]) - dp;
dp[idx] = a[i];
}
if(k >= n-j) {printf("A is a magic array.\n");continue;}
printf("A is not a magic array.\n");
}
return 0;
}