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| #include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 10010;
int n;
int a[N], q[N];
int f[N], g[N];
int main() {
while (scanf("%d", &n) != EOF) {
memset(f, 0, sizeof f);
memset(g, 0, sizeof g);
for (int i = 0; i < n; i++) scanf("%d", &a[i]);
int len = 0;
q[0] = -2e9;
for (int i = 0; i < n; i++) {
int l = 0, r = len;
while (l < r) {
int mid = l + r + 1 >> 1;
if (q[mid] < a[i]) l = mid;
else r = mid - 1;
}
f[i] = r + 1;
len = max(len, r + 1);
q[r + 1] = a[i];
}
len = 0;
q[n] = -2e9;
for (int i = n - 1; i >= 0; i--) {
int l = 0, r = len;
while (l < r) {
int mid = l + r + 1 >> 1;
if (q[mid] < a[i]) l = mid;
else r = mid - 1;
}
g[i] = r + 1;
len = max(len, r + 1);
q[r + 1] = a[i];
}
int res = 1;
for (int i = 1; i <= n; i++) {
res = max(res, min(f[i], g[i]) * 2 - 1);
}
cout << res << endl;
}
return 0;
}
|