Subarray Sum

Source

• lintcode: Subarray Sum

Given an integer array, find a subarray where the sum
of numbers is zero. Your code should return the index
of the first number and the index of the last number.

Example
Given [-3, 1, 2, -3, 4], return [0, 2] or [1, 3].

Note
There is at least one subarray that it's sum equals to zero.

Python

class Solution:
    """
    @param nums: A list of integers
    @return: A list of integers includes the index of the first number 
             and the index of the last number
    """
    def subarraySum(self, nums):
        # write your code here
        result=[]
        map={}

        map[0]=-1

        current_sum=0

        for i in range(len(nums)):
            current_sum+=nums[i]
            if current_sum in map:
                result.append(map[current_sum]+1)
                result.append(i)
                return result
            else:
                map[current_sum]=i
        return result

Java

public class Solution {
    /**
     * @param nums: A list of integers
     * @return: A list of integers includes the index of the first number 
     *          and the index of the last number
     */
    public ArrayList<Integer> subarraySum(int[] nums) {
        ArrayList<Integer> result = new ArrayList<Integer>();
        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
        map.put(0, -1);
        int current_sum=0;

        for(int i=0; i<nums.length; i++){
            current_sum += nums[i];
            if(map.containsKey(current_sum)){
                result.add(map.get(current_sum)+1);
                result.add(i);
                return result;
            }
            else{
                map.put(current_sum, i);
            }
        }
        return result;
    }
}