DailyProblem/addOperators.cpp at main · Inferno-coder/DailyProblem · GitHub

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class Solution {
public:
    void solve(int ind, string s, int target, vector<string>& res, string tmp, long long prev, long long sum) {
        if (ind == s.size()) {
            if (sum == target)
                res.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 = stoll(st);

            if (ind == 0)
                solve(i + 1, s, target, res, tmp + st, curr, curr);
            else {
                solve(i + 1, s, target, res, tmp + "+" + st, curr, sum + curr);
                solve(i + 1, s, target, res, tmp + "-" + st, -curr, sum - curr);
                solve(i + 1, s, target, res, tmp + "*" + st, prev * curr, sum - prev + prev * curr);
            }
        }

        return;
    }

    vector<string> addOperators(string s, int target) {
        vector<string> res;
        string tmp = "";
        long long prev = 0;

        solve(0, s, target, res, tmp, prev, 0);

        return res;
    }
};