Given an array of integers, return indices of the two numbers such that they add up to a specific target.
【1.|1. Two Sum.C#】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].
采用Hashtable或Dictionary来辅助存储，提升时间性能：
public class Solution {
public int[] TwoSum(int[] nums, int target) {
Hashtable numsTable = new Hashtable();
for (int i = 0;
i < nums.Length;
++i) {
if (numsTable.Contains(target - nums[i])) {
//使用Hashtable需要将其value转化为int，而使用Dictionary不需要，因为Hashtable中存储的是Object
return new int[] {(int)numsTable[target-nums[i]], i};
} else if (!numsTable.Contains(nums[i])) {
numsTable.Add(nums[i], i);
}
}
return new int[] {};
}
}
