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241-Different Ways to Add Parentheses.cpp
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241-Different Ways to Add Parentheses.cpp
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class Solution {
public:
vector<int> diffWaysToCompute(string input) {
unordered_map<string, vector<int>> m;
// m.push({"", vector<int>()});
m[""] = vector<int>();
return helper(input, m);
}
vector<int> helper(string input, unordered_map<string, vector<int>>& m){
if(m.count(input))
return m[input];
if(input.size() == 1){
m[input] = vector<int>{stoi(input)};
return m[input];
}
bool has_op = false;
vector<int> res;
for(int i = 0; i < input.size(); ++i){
if(!isdigit(input[i])){
has_op = true;
vector<int> left_res = helper(input.substr(0, i), m);
vector<int> right_res = helper(input.substr(i+1), m);
for(auto l : left_res){
for(auto r: right_res){
int tmp;
if(input[i] == '+')
tmp = l + r;
else if(input[i] == '-')
tmp = l - r;
else if(input[i] == '*')
tmp = l * r;
res.push_back(tmp);
}
}
}
}
if(!has_op)
res.push_back(stoi(input));
m[input] = res;
return res;
}
};
// class Solution {
// public:
// vector<int> diffWaysToCompute(string input) {
// vector<int> res;
// if(input.empty()) return res;
// if(input.size() == 1){
// res.push_back(stoi(input));
// return res;
// }
// bool has_op = false;
// for(int i = 0; i < input.size(); ++i){
// if(!isdigit(input[i])){
// has_op = true;
// vector<int> left_res = diffWaysToCompute(input.substr(0, i));
// vector<int> right_res = diffWaysToCompute(input.substr(i+1));
// for(auto l : left_res){
// for(auto r: right_res){
// int tmp;
// if(input[i] == '+')
// tmp = l + r;
// else if(input[i] == '-')
// tmp = l - r;
// else if(input[i] == '*')
// tmp = l * r;
// res.push_back(tmp);
// }
// }
// }
// }
// if(!has_op)
// res.push_back(stoi(input));
// return res;
// }
// };