[LeetCode]1. Two Sum java

/**1. Two Sum * @param nums * @param target * @return 数组中找两个数字，相加等于target */ public int[] twoSum(int[] nums, int target) { int[] ret = new int[2]; for (int i=0; i<nums.length; i++) { for (int j=i+1; j<nums.length; j++) { if (nums[i] + nums[j] == target) { ret[0] = i; ret[1] = j; } } } return ret; }

改进 利用hashmap存储数组，key为数组值，value对对应的下标

public int[] twoSum(int[] nums, int target) { int[] ret = new int[2]; HashMap<Integer, Integer> map = new HashMap<Integer, Integer>(); for (int i=0, len=nums.length; i<len; i++) { if (!map.containsKey(target-nums[i])) { map.put(nums[i], i); } else { ret[0] = i; ret[1] = map.get(target-nums[i]); } } return ret; } // beats 45.40%