JEDNAKOS of SPOJ

#include<bits/stdc++.h>

using namespace std;
typedef long long ll;

/** learnings
_compare true means small false means large
*/

int t[1000][5000];
int p[1000];
int makeNum(string s,int l,int r){
    int ans=0;
    for(int i=l;i<=r;i++){
        int pos = (int)(s[i]-'0');
        ans *= 10;
        ans += pos;
    }
    return ans;
}
int fun(string s,int sm,int l,int r){
    if(l==r+1)return INT_MAX-1;
    if(r-p[l]+1<=4){
        if(makeNum(s,p[l],r)==sm){
            return 0;
        }
    }
    int &res = t[l][sm];
    if(res!=-1)return res;
    int ans=INT_MAX-1;
    for(int k=p[l],cnt=1;(k<=r && cnt<=4);k++,cnt++){
        int pos = makeNum(s,p[l],k);
        int cur=INT_MAX-1;
        if(pos<=sm){
            cur=1+fun(s,sm-pos,k+1,r);
            ans = min(ans,cur);
        }
    }
    return res = ans;
}
void solve(){
    memset(t,-1,sizeof(t));
    string s;cin>>s;
    int sm=0,i,pd=0;
    int n = s.length();
    for(i=n-1;s[i]!='=';i--){
        int pos = (int)(s[i]-'0');
        if(pd==0)pd=1;
        else pd*=10;
        sm+=pos*pd;
    }
    p[i-1]=i-1;
    for(int j=i-2;j>=0;j--){
        p[j] = (s[j]=='0'?p[j+1]:j);
    }
    cout<<fun(s.substr(0,i),sm,0,i-1);
}
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
        solve();
}