【LeetCode 01】两数之和---- HashMap

目录

• 1、Question——TwoSum

 

1、Question——TwoSum

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

Answer

package com.demo.leetcode001; import java.util.HashMap; public class twoSum {       public static int[] iTwoSum(int[] nums, int target){             HashMap<Integer, Integer> m = new HashMap<Integer, Integer>();             int[] res = new int[2];             for(int i = 0; i < nums.length; i++){                   if(m.containsKey(target - nums[i])){                        res[1] = i;                        res[0] = m.get(target - nums[i]);                        break;                   }                   m.put(nums[i], i);             }             return res;       }       public static void main(String[] args) {             int[] nums = {2, 7, 11, 15};             int target = 9;             int[] res = iTwoSum(nums,target);             System.out.println(res[0]);             System.out.println(res[1]);       } }