https://leetcode.com/problems/two-sum/
Time Complexity : O(n^2) Space Complexity : O(1)
class Solution {
public int[] twoSum(int[] nums, int target) {
for(int i = 0; i < nums.length - 1; i++) {
for(int j = i + 1; j < nums.length; j++) {
if(nums[i] + nums[j] == target) return new int[]{i, j};
}
}
return null;
}
}Time Complexity : O(n) Space Complexity : O(n)
class Solution {
public int[] twoSum(int[] nums, int target) {
Map<Integer, Integer> numToIndex = new HashMap<>();
for (int i = 0; i < nums.length; i++) {
if (numToIndex.containsKey(target - nums[i])) {
return new int[]{numToIndex.get(target - nums[i]), i};
}
numToIndex.put(nums[i], i);
}
return new int[]{};
}
}