Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. The valid operators are +, - and *.
Example 1
Input: “2-1-1”.
((2-1)-1) = 0
(2-(1-1)) = 2
Output: [0, 2]
Example 2
Input: “2*3-4*5”
(2*(3-(4*5))) = -34
((2*3)-(4*5)) = -14
((2*(3-4))*5) = -10
(2*((3-4)*5)) = -10
(((2*3)-4)*5) = 10
Output: [-34, -14, -10, -10, 10]
Solution:
public class Solution {
public List<Integer> diffWaysToCompute(String input) {
List<Integer> ans = new ArrayList<>();
for(int i=0; i<input.length(); i++){
char c = input.charAt(i);
if(c=='+'||c=='-'||c=='*'){
List<Integer> part1 = diffWaysToCompute(input.substring(0, i));
List<Integer> part2 = diffWaysToCompute(input.substring(i+1));
for(Integer p1 : part1){
for(Integer p2 : part2){
switch(c){
case '+' : ans.add(p1+p2); break;
case '-' : ans.add(p1-p2); break;
case '*' : ans.add(p1*p2); break;
}
}
}
}
}
if(ans.size()==0) ans.add(Integer.valueOf(input));
return ans;
}
}