哈希（6）

原题：

/**
 * Created by gouthamvidyapradhan on 09/03/2017.
 * Given an array of integers, return indices of the two numbers such that they add up to a specific target.
 * <p>
 * You may assume that each input would have exactly one solution, and you may not use the same element twice.
 * <p>
 * Example:
 * Given nums = [2, 7, 11, 15], target = 9,
 * <p>
 * Because nums[0] + nums[1] = 2 + 7 = 9,
 * return [0, 1].
 */

答案：

public class TwoSum {
    HashMap<Integer, Integer> map = new HashMap<>();

    public int[] twoSum(int[] nums, int target) {
        int[] result = new int[2];

        for (int i : nums) {
            if (map.keySet().contains(i)) {
                int count = map.get(i);
                map.put(i, ++count);
            } else {
                map.put(i, 1);
            }
        }

        for (int i = 0, l = nums.length; i < l; i++) {
            int ele = nums[i];
            int req = target - ele;
            if (map.keySet().contains(req)) {
                result[0] = i;
                if (ele == req) {
                    int count = map.get(req);
                    if (count > 1) {
                        for (int j = i + 1; j < l; j++) {
                            if (nums[j] == req) {
                                result[1] = j;
                                return result;
                            }
                        }
                    }
                } else {
                    for (int j = i + 1; j < l; j++) {
                        if (nums[j] == req) {
                            result[1] = j;
                            return result;
                        }
                    }
                }
            }
        }
        return result;
    }
}