练习编程之leetcode篇----------(1)Two Sum

Given an array of integers, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

You may assume that each input would have exactly one solution.

Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2

 

解答：

public class Solution {
    public int[] twoSum(int[] numbers, int target) {
        //先给数组开辟空间
        int []result=new int[2];
        //先把所有数据存放到HashMap中去
        HashMap<Integer, Integer> tempSave=new HashMap<Integer, Integer>();
        //把所有的数据存放发HashMap中去
        for(int i=0;i<numbers.length;i++)
        {
            tempSave.put(numbers[i], i);
        }
        //测试数据中的每一个元素
        for(int j=0;j<numbers.length;j++)
        {
            //如果找到的话，则加入到result中去，并停止寻找
            if(tempSave.containsKey(target-numbers[j]))
            {
                if((j+1)!=(tempSave.get(target-numbers[j])+1))
                {
                    result[0]=j+1;
                    result[1]=tempSave.get(target-numbers[j])+1;
                    break;
                }
                
            }
        }
        return result;     
         
    }
}