TwoSum.java

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

class Solution {
 public int[] twoSum(int[] nums, int target) {

 Map<Integer, Integer> numMap = new HashMap<>();
 
 for (int i = 0; i < nums.length; i++) {
 int complement = target - nums[i];
 if (numMap.containsKey(complement)) {
 return new int[]{i, numMap.get(complement)};
 }
 numMap.put(nums[i], i);
 }
 return new int[0];
 }
}

class Solution2 {
 public int[] twoSum(int[] nums, int target) {

 int[] sorted = Arrays.copyOf(nums, nums.length);
 Arrays.sort(sorted);

 int i = 0;
 int j = nums.length - 1;
 
 while (i < j) {
 int sum = sorted[i] + sorted[j];
 if (sum == target) {
 
 }
 else if (sum > target) {
 j--;
 }
 else if (sum < target) {
 i++;
 }
 else
 break;
 }
 return new int[0];
 }
}