标签：
1. Given an array of integers, return indices of the two numbers such that they add up to a specific target.
问题：
1.数组是否有序
2. 数组排序
// sorting array
Arrays.sort(iArr)
方法1：O（n^2）
public class Solution { public int[] twoSum(int[] nums, int target) { int[] result = new int[2]; for (int i = 0; i < nums.length; i++){ for (int j = i+1; j < nums.length; j++){ if(nums[i] + nums[j] == target){ result [0] = i; result [1] = j; } } } return result; } }
2. Two sum II Input array is sorted (HashMap, 无相同元素
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.
public class Solution { public int[] twoSum(int[] nums, int target) {
int [] result = new int[2]; HashMap<Integer, Integer> hm = new HashMap<Integer, Integer>(); for(int i = 0; i < nums.length; i++){ hm.put(nums[i], i); } for(int i = 0; i < nums.length; i++){ if(hm.containsKey(target-nums[i]) && target != 2 * nums[i]){ result[0] = i; result[1] = hm.get(target-nums[i]); break; } } return result; }
}
3. Two sum III
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原文地址：http://www.cnblogs.com/beily/p/5683312.html
