GFG_Daily_Problem/Expression Add Operators.cpp at main · Thelalitagarwal/GFG_Daily_Problem · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
class Solution {
  public:
     void f(int ind,string s,int target,vector<string> &ans,string tmp,long long prev,long long res){
      if(ind==s.size()){
          if(res==target)
          ans.push_back(tmp);
          return;
      }
      string st="";
      long long curr=0;
      for(int i=ind;i<s.size();i++){
          if(i>ind && s[ind]=='0')
          break;
          st+=s[i];
          curr=curr*10+s[i]-'0';
          if(ind==0)
          f(i+1,s,target,ans,tmp+st,curr,curr);
          else{
              f(i+1,s,target,ans,tmp+"+"+st,curr,res+curr);
              f(i+1,s,target,ans,tmp+"-"+st,-curr,res-curr);
              f(i+1,s,target,ans,tmp+"*"+st,prev*curr,res-prev+prev*curr);
          }
      }
      return;
  }
    vector<string> addOperators(string s, int target) {
        vector<string> ans;
        string tmp="";
        long long prev=0;
        f(0,s,target,ans,tmp,prev,0);
        return ans;
    }
};