Subarray Sum

Easy Subarray Sum

21%

Accepted

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.

Have you met this question in a real interview? 

Yes

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.

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) {
        // write your code here
        ArrayList<Integer> res = new ArrayList<Integer>();
        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
        map.put(0, -1);
        int sum = 0;
        for(int i = 0; i < nums.length; i++){
            sum += nums[i];
            if(map.containsKey(sum)){
                res.add(map.get(sum)+1);
                res.add(i);
                return res;
            }
            map.put(sum, i);
        }
        return res;
    }
}