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; } }
LC 241. Different Ways to Add Parentheses
原文：https://www.cnblogs.com/ethanhong/p/10278465.html