Easy 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.
Thoughts
Code
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) {
Map<Integer, Integer> preSum = new HashMap<>();
ArrayList<Integer> res = new ArrayList<>();
preSum.put(0, -1); // to handle cases like [-1, 1]
for (int i = 0, sum = 0; i < nums.length; i++) {
sum += nums[i];
if (preSum.containsKey(sum)) {
res.add(preSum.get(sum) + 1);
res.add(i);
return res;
} else {
preSum.put(sum, i);
}
}
return res;
}
}