POJ 2127 LCIS DP

Posted 2020-09-20

http://poj.org/problem?id=2127

#include <iostream>
#include <algorithm>
#include <cstring>
#include <queue>
#include <cstdio>
#include <map>
#include <vector>
using namespace std;
const int N=5e2+20;
const int inf=2e8;
//题意:a,b两个数组,长度<=500,a[i],b[i]<=1e9,求出a,b最长公共递增子序列?
//设dp[i][j] a的前i个字符和b的前j个字符&&以b[j]结尾的LCIS长度 
//a[i]!=b[j]: dp[i][j]=dp[i-1][j]
//a[i]==b[j]: dp[i][j]=max(dp[i-1][k]+1 ) ( 1<=k<j,b[k]<b[j]=a[i])  
 
int dp[N][N];//a的前i个字符和b的前j个字符&&以b[j]结尾的LCIS长度 
int path[N][N];//LCIS 以b[j]结尾,记录此时决策 
int n,m,a[N],b[N];
vector<int> res;
int main()
{
	while(cin>>n)
	{
		res.clear();
		int p,q;
		for(int i=1;i<=n;i++)
			cin>>a[i];
		cin>>m;
		for(int i=1;i<=m;i++)
			cin>>b[i];
		memset(dp,0,sizeof(dp));
		memset(path,0,sizeof(path));
		int ans=0,mj;
		for(int i=1;i<=n;i++)
		{
			int mx=0;
			for(int j=1;j<=m;j++)
			{
				
				dp[i][j]=dp[i-1][j];//a[i]!=b[j]
				path[i][j]=-1;
				if(b[j]<a[i]&&dp[i-1][j]>mx)
				{
					mx=dp[i-1][j];
					mj=j;
				}
				else if(a[i]==b[j])
				{
					dp[i][j]=mx+1;
					path[i][j]=mj;
				}
				if(ans<dp[i][j])
				{
					ans=dp[i][j];
					p=i,q=j;
				}	
			}
		}
		cout<<ans<<endl;
		while(ans)
		{
			if(path[p][q]>-1)
			{
				ans--;
				res.push_back(b[q]);
				q=path[p][q];
			}
			p--;
		}
		for(int i=res.size()-1;i>=0;i--)
			printf("%d%c",res[i],i==0?‘\n‘:‘ ‘);
	}

	return 0;
}