Longest common sub sequences(LCS)

gistfile1.txt

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

int main()
{
    string r,s1,s2;int ls1,ls2,co=0;
    cin>>s1;
    cin>>s2;
    ls1=s1.length();
    ls2=s2.length();
    int arr[ls1+1][ls2+1];


    for(int i=0;i<=ls1;i++){

       for(int j=0;j<=ls2;j++){

       if (i == 0 || j == 0)
         arr[i][j] = 0;

        else if(s1[i-1]==s2[j-1]){
             arr[i][j]=arr[i-1][j-1]+1;


           }

        else
           arr[i][j]=max(arr[i-1][j],arr[i][j-1]);


        }

    }

    cout<<arr[ls1][ls2]<<endl;


    int p=ls1,q=ls2;

    while(p>0&&q>0){

        if(s1[p-1]==s2[q-1]){

          r[co]=s1[p-1];
          co++;
          p--;q--;
        }

     else if(arr[p-1][q]>arr[p][q-1])
           p--;
      else
           q--;

    }
    for(int m=co-1;m>=0;m--)
        cout<<r[m];


    return 0;
}