HDU 1423 Greatest Common Increasing Subsequence(LICS入门,只要求出最长数)

Greatest Common Increasing Subsequence

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 5444    Accepted Submission(s): 1755

Problem Description
This is a problem from ZOJ 2432.To make it easyer,you just need output the length of the subsequence.
 
Input
Each
sequence is described with M - its length (1 <= M <= 500) and M
integer numbers Ai (-2^31 <= Ai < 2^31) - the sequence itself.
 
Output
output print L - the length of the greatest common increasing subsequence of both sequences.
 
Sample Input
1

5
1 4 2 5 -12
4
-12 1 2 4

 
Sample Output
2
 
Source
 
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四种方法代码:

每一种都按照我觉得最容易理解的思路和最精简的写法写了,有些地方i 或者 i-1都可以,不必纠结。

#include<algorithm>
#include<string>
#include<string.h>
#include<stdio.h>
#include<iostream>
using namespace std;
#define N 505 int a[N],l1,l2,b[N],ma,f[N][N],d[N];
void solve1()//O(n^4)
{
ma = ;
memset(f, , sizeof(f) );
for(int i = ; i <= l1; i++)
for(int j = ; j <= l2; j++)
{
if(a[i-] == b[j-])
{
int ma1 = ;
for(int i1 = ; i1 < i; i1++)
for(int j1 = ; j1 < j; j1++)
if(a[i1-] == b[j1-] && a[i1-] < a[i-] && f[i1][j1] > ma1)//实际上a[i-1]==b[j1-1]可以省,因为既然f[i1][j1]+1>f[i][j]了,
ma1 = f[i1][j1]; /*说明肯定a[i-1]==b[j1-1]了,因为这种解法只有当a[i-1]==b[j-1]时,f[i][j]才不等于0*/
f[i][j] = ma1 + ;
}
ma = max(ma, f[i][j]);
}
cout<<ma<<endl;
}
void solve2()//O(n^3)
{
ma = ;
memset(f, , sizeof(f) );
for(int i = ; i <= l1; i++)
for(int j = ; j <= l2; j++)
{
f[i][j] = f[i-][j];
if(a[i-] == b[j-])
{
int ma1 = ;
for(int j1 = ; j1 < j; j1++)
{
if(b[j1-] < b[j-] && f[i-][j1] > ma1)
ma1 = f[i-][j1];
}
f[i][j] = ma1 + ;
}
ma = max(ma, f[i][j]);
}
cout<<ma<<endl;
}
void solve3()//O(n^2)
{
memset(f, , sizeof(f) );
for(int i = ; i <= l1; i++)
{
int ma1 = ;
for(int j = ; j <= l2; j++)
{
f[i][j] = f[i-][j];//带这种的一般都能压缩一维空间,也就是简化空间复杂度
if(a[i-] > b[j-] && f[i-][j] > ma1)
ma1 = f[i-][j];
if(a[i-] == b[j-])
f[i][j] = ma1 + ;
}
}
ma = -;
for(int j = ;j <= l2; j++)
ma=max(ma,f[l1][j]); cout<<ma<<endl;
}
void solve4()//O(n^2)//优化空间复杂度
{
ma = ;
memset(d, , sizeof(d) );
for(int i = ; i <= l1; i++)
{
int ma1 = ;
for(int j = ; j <= l2; j++)
{
if(a[i-] > b[j-] && d[j] > ma1)
ma1 = d[j];
if(a[i-] == b[j-])
d[j] = ma1 + ;
}
}
ma = -;
for(int j = ;j <= l2; j++)
ma = max(ma, d[j]); cout<<ma<<endl;
} int main()
{
int T;cin>>T;
while(T--)
{
scanf("%d", &l1);
for(int i = ; i < l1; i++)
scanf("%d", &a[i]);
scanf("%d", &l2);
for(int i = ; i < l2; i++)
scanf("%d", &b[i]);
// solve1();
// solve2();
// solve3();
solve4(); if(T)
printf("\n");
} return ;
}
/*
99 5
1 4 2 5 -12
4
-12 1 2 4 9
3 5 1 6 7 9 1 5 13
6
4 6 13 9 13 5
*/
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