http://codeforces.com/contest/583/problem/D
原题: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.
题目大意:有长度为n的数组a(n <= 100),其中a[i] <= 300,这个a数组可以重复T次,问他的最长上升子序列是多少?
思路:我们可以发现,这个数组如果要全部都算上的,那么在t<=n的情况下,他的最长上升子序列一定会遍历一次a数组。所以我们就只需要把原来的数组扩大n倍,然后求他的LIS。
这样以后我们发现,后面的重复的次数一定是原来数组里面出现次数(假定重复次数k为最多)最多的数值,所以ans = Lis的长度 + k * T - min(n, T);
复杂度 O(n*n*logn)
//看看会不会爆int!数组会不会少了一维!
//取物问题一定要小心先手胜利的条件
#include <bits/stdc++.h>
using namespace std;
#pragma comment(linker,"/STACK:102400000,102400000")
#define LL long long
#define ALL(a) a.begin(), a.end()
#define pb push_back
#define mk make_pair
#define fi first
#define se second
#define haha printf("haha\n")
const int maxn = + ;
int a[maxn * maxn];
int n, T;
vector<int> ve; int solve(int t){
int len = t * n;
for (int i = ; i < t; i++){
for (int j = ; j <= n; j++){
a[n * i + j] = a[j];
}
}
for (int i = ; i <= n * t; i++){
int pos = upper_bound(ve.begin(), ve.end(), a[i]) - ve.begin();
if (pos == ve.size()) ve.push_back(a[i]);
else ve[pos] = a[i];
}
return ve.size();
} int cnt[maxn * maxn];
int main(){
cin >> n >> T;
int maxval = , k = ;
for (int i = ; i <= n; i++){
scanf("%d", a + i);
cnt[a[i]]++;
k = max(cnt[a[i]], k);
}
int ans = solve(min(n, T));
//printf("ans = %d k = %d T - min(n, T) = %d\n", ans, k, T - min(n, T));
printf("%d\n", ans + k * (T - min(n, T)));
return ;
}