ARTS打卡计划第三周-Algorithm

Posted 2021-11-27 dongqisilent

1. 两数之和

提供了2种揭发

public class Solution1 {
	
	 public int[] twoSum(int[] nums, int target) {
		 int len=nums.length;
		 int[] result = new int[2];
		 for(int i=0;i<len;i++) {
			 for(int j=i+1;j<len;j++) {
				 if(nums[i]==target-nums[j]) {
					 result[0]=i;
					 result[1]=j;
				 }
				 
			 }
		 }
		 return result;
	        
	 }
	
	 public int[] twoSum1(int[] nums, int target) {
		 int len=nums.length;
		 int[] result = new int[2];
		 HashMap<Integer, Integer> map = new HashMap<>();
		 for(int i=0;i<len;i++) {
			 map.put(nums[i], i);
			 
		 }
		 
		 for(int i=0;i<len;i++) {
			 if(map.containsKey(target-nums[i])) {
				 if(i==map.get(target-nums[i])) {
					 continue;
				 }
				 result[0]=i;
				 result[1]=map.get(target-nums[i]);
				 break;
			 }
		 }
		 return result;
	        
	 }
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] nums = new int[] {2, 7, 11, 15};
		Solution1 s = new Solution1();
		for(int i:s.twoSum1(nums,9)) {
			System.err.println(i);

		}
	}

}