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"
Output:[0, 2]
Explanation:
((2-1)-1) = 0
(2-(1-1)) = 2
Example 2:
Input:"2*3-4*5"
Output:[-34, -14, -10, -10, 10]
Explanation:
(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
Runtime: 4 ms, faster than 77.90% of Java online submissions for Different Ways to Add Parentheses.
class Solution {
public List<Integer> diffWaysToCompute(String input) {
List<Integer> ret = new ArrayList<>();
for(int i=0; i<input.length(); i++){
if(input.charAt(i) == '+' ||
input.charAt(i) == '-' ||
input.charAt(i) == '*') {
String part1 = input.substring(0,i);
String part2 = input.substring(i+1);
List<Integer> part1ret = diffWaysToCompute(part1);
List<Integer> part2ret = diffWaysToCompute(part2);
for(int x : part1ret){
for(int y : part2ret){
switch (input.charAt(i)) {
case '+' : ret.add(x + y);
break;
case '-' : ret.add(x - y);
break;
case '*' : ret.add(x * y);
break;
}
}
}
}
}
if(ret.size() == 0) ret.add(Integer.valueOf(input));
return ret;
}
}