POJ 1458 Common Subsequence

#include <iostream>
#include <string>
#include <string.h>

using namespace std;

int dp[1000][1000];

int main()
{
string str1,str2;
while(cin>>str1>>str2)
{
int len1,len2;
len1=str1.size();
len2=str2.size();

memset(dp,0,sizeof(dp));

for(int i=1;i<=len1;i++)
{
for(int j=1;j<=len2;j++)
{
if(str1[i-1]==str2[j-1])
dp[i][j]=dp[i-1][j-1]+1;
else
dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
}
}
cout<<dp[len1][len2]<<endl;
}
return 0;
}