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package Algorithms.lintcode.array;

import java.util.ArrayList;

import java.util.HashMap;

public class SubarraySum {

/**

* @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

int len = nums.length;

ArrayList<Integer> ret = new ArrayList<Integer>();

HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();

// We set the index -1 sum to be 0 to let us more convient to count.

map.put(0, -1);

int sum = 0;

for (int i = 0; i < len; i++) {

sum += nums[i];

if (map.containsKey(sum)) {

// For example:

// -3 1 2 -3 4

// SUM: 0 -3 -2 0 -3 1

// then we got the solution is : 0 - 2

ret.add(map.get(sum) + 1);

ret.add(i);

return ret;

}

// Store the key:value of sum:index.

map.put(sum, i);

}

return ret;

}

}