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
numbers=[2, 7, 11, 15], target=9
return [1, 2]
分析：
利用hashMap把值和对应的Index放在里面。然后对于剩余的值，在hashmap里查找就可以了。
1 public class Solution { 2 /* 3 * @param numbers : An array of Integer 4 * @param target : target = numbers[index1] + numbers[index2] 5 * @return : [index1 + 1, index2 + 1] (index1 < index2) 6 cnblogs.com/beiyeqingteng/ 7 */ 8 public int[] twoSum(int[] numbers, int target) { 9 HashMap<Integer,Integer> map = new HashMap<Integer, Integer>(); 10 11 for (int i = 0; i < numbers.length; i++) { 12 if (map.containsKey(numbers[i])) { 13 int[] result = {map.get(numbers[i]) + 1, i + 1}; 14 return result; 15 } 16 map.put(target - numbers[i], i); 17 } 18 19 int[] result = {}; 20 return result; 21 } 22 }
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原文：http://www.cnblogs.com/beiyeqingteng/p/5639344.html