Codves 1044 拦截导弹 —1999年NOIP全国联赛提高组
一遍最长不上升子序列, 一遍严格上升子序列。
n方代码:
#include <cstdio>
#include <cstring>
#include <iostream>
#include <cstdlib>
using namespace std;
#define MAXN (20+2)
int a[MAXN], dp[MAXN];
int main()
{
int n = 1;
while(scanf("%d", &a[n]) != EOF)
n ++;
n --;
for(int i = 1; i <= n; i ++) dp[i] = 1;
for(int i = 1; i <= n; i ++)
for(int j = i+1; j <= n; j ++)
if(a[j] < a[i])
dp[j] = max(dp[j], dp[i]+1);
int ans = 0;
for(int i = 1; i <= n; i ++)
ans = max(ans, dp[i]);
cout << ans << endl;
memset(dp,0,sizeof(dp));
for(int i = 1; i <= n; i ++) dp[i] = 1;
for(int i = 1; i <= n; i ++)
for(int j = i+1; j <= n; j ++)
if(a[j] > a[i])
dp[j] = max(dp[j], dp[i]+1);
ans = 0;
for(int i = 1; i <= n; i ++)
ans = max(ans, dp[i]);
cout << ans << endl;
return 0;
}
nlogn :
翻转序列
#include <iostream>
#include <cstdio>
#include <queue>
#include <cstring>
#include <cstdlib>
#include <algorithm>
using namespace std;
#define MAXN (20+2)
int a[MAXN], dp[MAXN], Za[MAXN];
#define INF (1e9)
int main()
{
int n = 1;
while(scanf("%d", &a[n]) != EOF)
n ++;
n --;
for(int i = 1; i <= n; i ++)
Za[n-i+1] = a[i];
fill(dp+1, dp+n+1, INF);
for(int i = 1; i <= n; i ++)
dp[upper_bound(dp+1, dp+n+1, Za[i])-dp] = Za[i];
cout << (lower_bound(dp+1, dp+n+1, INF)-dp-1) << endl;
fill(dp+1, dp+n+1, INF);
for(int i = 1; i <= n; i ++)
dp[lower_bound(dp+1, dp+n+1, a[i])-dp] = a[i];
cout << (lower_bound(dp+1, dp+n+1, INF)-dp-1) << endl;
return 0;
}