算法-哈希表-两个数的和

class Solution {
    
    
    public int[] twoSum(int[] nums, int target) {
    
    
        if(nums == null || nums.length == 0) {
    
    
            return new int[0];
        }
        HashMap<Integer, Integer> map = new HashMap<>();
        for(int i = 0; i < nums.length; i++) {
    
    
            if(map.containsKey(target - nums[i])) {
    
    
                return new int[] {
    
    map.get(target - nums[i]), i};
            }else{
    
    
                map.put(nums[i], i);
            }
        }
        return new int[0];
    }
}