题解:
状态表示1: f[i]是从1开始到以第i个点为结尾的最长上升子序列的长度
状态表示2: g[i]是从n开始到以第i个点为结尾的最长上升子序列的长度
状态计算: f[i] = max(f[1~i-1] + 1, f[i]) g[i] = max(g[i + 1~n] + 1, g[i])
#include <iostream>
#include <algorithm>
#include <cstring>
typedef long long ll;
using namespace std;
const int N = 110;
int n;
int f[N], g[N];
int h[N];
void solve()
{
cin >> n;
int res = 1;
for(int i = 1; i <= n; i ++ ) cin >> h[i];
for(int i = 1; i <= n; i ++ )
f[i] = 1, g[i] = 1;
for(int i = 1; i <= n; i ++ )
for(int j = 1; j < i; j ++ )
if(h[j] < h[i])
{
f[i] = max(f[i], f[j] + 1);
res = max(f[i], res);
}
for(int i = n; i >= 1; i -- )
for(int j = n; j > i; j -- )
if(h[j] < h[i])
{
g[i] = max(g[j] + 1, g[i]);
res = max(res, g[i]);
}
cout << res << endl;
}
int main()
{
int test; cin >> test;
while(test --) solve();
return 0;
}
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