Shared code

#include<bits/stdc++.h>
using namespace std;
#define fastio() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define ff first
#define ss second
#define PI 3.141592653589793238462
#define INF 1e18
#define mod 1000000007
#define nline "\n"
#define pb push_back
#define popb pop_back
#define mp make_pair
#define rz resize
#define all(v) v.begin(), v.end()
#define fo(x,y) for(int i=x;i<y;i++)
#define fo1(x,y) for(int i=x;i<y;i++)
#define fo2(x,y) for(int j=x;j<y;j++)
#define pii pair<int,int>
#define tc int t;cin>>t;while(t--)
#ifndef ONLINE_JUDGE
#define debug(x)cerr<<#x<<" ";vprint(x);cerr<<endl;
#define debug2(x,y)cerr<<#x<<" ";vprint(x);cerr<<" ";cerr<<#y<<" ";vprint(y);cerr<<endl;
#else
#define debug(x);
#define debug2(x,y);
#endif
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
void vprint(int a){cerr<<a;}
void vprint(ll a){cerr<<a;}
void vprint(ull a){cerr<<a;}
void vprint(char a){cerr<<a;}
void vprint(double a){cerr<<a;}
void vprint(bool a){cerr<<a;}
void vprint(string a){cerr<<a;}
void vprint(long double a){cerr<<a;}
template<class T>void vprint(vector<T> v1){cerr<<"[";for(T i:v1){vprint(i);cerr<<" ";}cerr<<"]";}
template<class T>void vprint(set<T>s1){cerr<<"[";for(T i:s1){vprint(i);cerr<<" ";}cerr<<"]";}
template<class T>void vprint(multiset<T>s1){cerr<<"[";for(T i:s1){vprint(i);cerr<<" ";}cerr<<"]";}
template<class T,class P>void vprint(pair<T,P>p1){cerr<<"{";vprint(p1.ff);cerr<<",";vprint(p1.ss);cerr<<"}";}
template<class T,class P>void vprint(map<T,P>m1){cerr<<"[";for(auto i:m1){vprint(i);cerr<<" ";}cerr<<"]";}
template<class T>void vprint(vector<vector<T>>vec){for(int i=0;i<vec.size();i++){vprint(vec[i]);cerr<<endl;}}
template<class T,class P>void vprint(vector<pair<T,P>>v){cerr<<"[";for(auto i:v)vprint(i);cerr<<"]";cerr<<endl;}
template<class T,class P>void vprint(set<pair<T,P>>s){cerr<<"[";for(auto i:s)vprint(i);cerr<<"]";}
template<class T>void vprint(list<T>l){cerr<<"[";for(auto i:l){vprint(i);cerr<<" ";}cerr<<"]";}
template<class T,class P>void vprint(list<pair<T,P>>l){cerr<<"[";for(auto i:l)vprint(i);cerr<<"]";}
template<class T,class P>void vprint(unordered_map<T,P>m){cerr<<"[";for(auto i:m)vprint(i);cerr<<"]";}
template<class T,class P>void vprint(map<T,vector<pair<T,P>>>graph){for(auto i:graph){cerr<<"[";vprint(i.ff);cerr<<":";vprint(i.ss);cerr<<"]";}}
template<class T>void swap(T *a,T *b){T tmp;tmp=*a;*a=*b;*b=tmp;}

int ways(string str1,string str2,int i,int j,vector<vector<int>>&dp)
{

  if(i==0)
  return dp[i][j]=j;

  if(j==0)
  return dp[i][j]=i;  

  if(dp[i][j]!=-1)
  return dp[i][j];  

  if(str1[i-1]==str2[j-1])
  return dp[i][j]=ways(str1,str2,i-1,j-1,dp);
  else
  {
    int add=ways(str1,str2,i,j-1,dp);

    int remove=ways(str1,str2,i-1,j,dp);

    int replace=ways(str1,str2,i-1,j-1,dp);

    dp[i][j]=1+min(add,min(remove,replace));

    return dp[i][j];
  }   

}

void solve()
{

  string str1,str2;

  cin>>str1>>str2;

  int s1=str1.size(),s2=str2.size();

  vector<vector<int>>dp(s1+1,vector<int>(s2+1,-1));

  cout<<ways(str1,str2,s1,s2,dp);
  
}

int main() 
{
  #ifndef ONLINE_JUDGE
  freopen("error.txt","w",stderr);
  #endif
  fastio();  
  solve();
  return 0;
}