LeetCode -- Different Ways to Add Parentheses

public class Solution {
public IList<int> DiffWaysToCompute(string input) 
{
	List<int> result = new List<int>();
        if (input == null || input.Length == 0) {
            return result;
        }
        
        for (int i = 0; i < input.Length; i++) {
            char c = input[i];
            if (c != ‘+‘ && c != ‘-‘ && c != ‘*‘) {
                continue;
            }
            
            var left = DiffWaysToCompute(input.Substring(0, i));
            var right = DiffWaysToCompute(input.Substring(i + 1, input.Length- i - 1));
            
            for (var j = 0;j < left.Count; j++) {
                for (var k = 0;k < right.Count; k++) {
                    if (c == ‘+‘) {
                        result.Add(left[j] + right[k]);
                    } else if (c == ‘-‘) {
                        result.Add(left[j] - right[k]);
                    } else if (c == ‘*‘) {
                        result.Add(left[j] * right[k]);
                    }
                }
            }
        }
        
        if (result.Count == 0) {
            result.Add(int.Parse(input));
        }
        
        return result;
}
}

LeetCode -- Different Ways to Add Parentheses

原文：http://blog.csdn.net/lan_liang/article/details/48575941