January 15, 2019

1. Two Sum

Java:

class Solution {
    public int[] twoSum(int[] nums, int target) {
        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            if (map.containsKey(nums[i])) {
                int[] res = new int[2];
                res[0] = map.get(nums[i]);
                res[1] = i;
                return res;
            } else {
                map.put(target - nums[i], i);
            }
        }
        return null;
    }
}

Python:

class Solution:
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        nums_set = {}
        for idx, val in enumerate(nums):
            if val in nums_set:
                return [nums_set[val], idx]
            else:
                nums_set[target - val] = idx