【LeetCode100】--- 1.两数之和【复习回顾】

class Solution {
    public int[] twoSum(int[] nums, int target) {
        int n = nums.length;
        for(int i = 0; i < n; i++){
            for(int j = i+1; j<n; j++){
                if(nums[i] + nums[j] == target){
                    return new int[]{i,j};
                }
            }
        }
        return new int[]{-1,-1};
    }
}

class Solution {
    public int[] twoSum(int[] nums, int target) {
        Map<Integer,Integer> map = new HashMap<>();
        int n = nums.length;

        for(int i = 0; i<n; i++){
            int x = target-nums[i];
            if(map.containsKey(x)){
                return new int[]{map.get(x),i};
            }
            map.put(nums[i],i);
        }
        return new int[]{-1,-1};
    }
}