算法学习笔记——两数之和

两数相加

public class 两数相加 {
    public static void main(String[] args) {
        int[] arr={2,7,11,15};
        int target=9;
        System.out.println(Arrays.toString(两数相加.twoNums(arr,target)));  

    public static int[] twoNums(int[] nums, int target){
        HashMap<Integer,Integer> m=new HashMap<>();
        for(int i=0;i<nums.length;i++){
            if(m.containsKey(target-nums[i])){
                return new int[]{m.get(target-nums[i]),i};
            }
            m.put(nums[i],i);
        }
        throw new IllegalArgumentException("No two sum value");
    }
}

  	//暴力破解	
	int[] nums = new int[]{2, 7, 11, 15};
    int[] arr1 = new int[2];

        int target = 9;
        for (int i = 0; i <= nums.length - 1; i++) {
            int nums1 = target - nums[i];
            for (int j = i + 1; j <= nums.length - 1; j++) {
                if (nums1 == nums[j]) {
                    arr1[0] = i;
                    arr1[1] = j;
                }
            }
        }
        System.out.println(Arrays.toString(arr1));*/
    }