Codeforces Round #323 (Div. 2) D. Once Again... 乱搞+LIS

D. Once Again...
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

You are given an array of positive integers a1, a2, ..., an × T of length n × T. We know that for any i > n it is true that ai = ai - n. Find the length of the longest non-decreasing sequence of the given array.

Input

The first line contains two space-separated integers: nT (1 ≤ n ≤ 100, 1 ≤ T ≤ 107). The second line contains n space-separated integers a1, a2, ..., an (1 ≤ ai ≤ 300).

Output

Print a single number — the length of a sought sequence.

Examples
input
4 3
3 1 4 2
output
5
Note

The array given in the sample looks like that: 3, 1, 4, 2, 3, 1, 4, 2, 3, 1, 4, 2. The elements in bold form the largest non-decreasing subsequence.

 题目链接:http://codeforces.com/contest/583/problem/D

题意:给你一个序列n,有T个连续这样的序列,求最长不下降子序列的长度;

思路:发现T很大,n很小对吧,

   显然中间肯定是有一段是连续的相同的数对吧;

   开始想前面取一个LIS,最后取一个LIS,中间相同,数量最多的那个数;

     这个做法错误,可能后面的前一个还能多取;

   如果T<=n比较小,我们只需要暴力跑LIS即可;

   现在讨论T>n的情况;

   然后发现只有n个数,也就是说最后的LIS最多只有n段不同的数;

   也就是说我们只需要拿出n段序列出来,跑LIS即可;

   因为最多n段,然后取完n段,多余的可以从中间插入;

   

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<queue>
#include<algorithm>
#include<stack>
#include<cstring>
#include<vector>
#include<list>
#include<set>
#include<map>
using namespace std;
#define ll long long
#define pi (4*atan(1.0))
#define mk make_pair
#define eps 1e-7
#define bug(x)  cout<<"bug"<<x<<endl;
const int N=1e5+10,M=1e6+10,inf=2147483647;
const ll INF=1e18+10,mod=1000000007;

///   数组大小
int arr[N],ans[N],len;
int binary_search(int i)
{
    int left,right,mid;
    left=0,right=len;
    while(left<right)
    {
        mid = left+(right-left)/2;
        if(ans[mid]>arr[i]) right=mid;
        else left=mid+1;
    }
    return left;
}
int LIS(int p)
{
    ans[1] = arr[1];
    len=1;
    for(int i=2; i<=p; ++i)
    {
        if(arr[i]>=ans[len])
            ans[++len]=arr[i];
        else
        {
            int pos=binary_search(i);
            ans[pos] = arr[i];
        }
    }
    return len;
}
int flag[N];
int main()
{
    int n,T,maxx=0;
    scanf("%d%d",&n,&T);
    for(int i=1;i<=n;i++)
        scanf("%d",&arr[i]),flag[arr[i]]++,maxx=max(maxx,flag[arr[i]]);
    for(int i=1;i<n;i++)
        for(int j=1;j<=n;j++)
            arr[i*n+j]=arr[j];
    if(n>=T)printf("%d
",LIS(n*T));
    else printf("%d
",LIS(n*n)+maxx*(T-n));
    return 0;
}
原文地址:https://www.cnblogs.com/jhz033/p/6726984.html