LeetCode-1-两数之和

题目链接：https://leetcode-cn.com/problems/two-sum/

方法：利用unordered_map哈希查找，先建立哈希表O(n)，再查找O(n)

class Solution {
public:
	vector<int> twoSum(vector<int>& nums, int target) {
		vector<int>result;
		int d;
		unordered_map<int, int>unomap;  //标准库哈希表容器
		for (int i = 0; i < nums.size(); ++i)
		{
			unomap[nums[i]] = i;  //将值存为key 下标存为value
		}
		for (int i = 0; i < nums.size(); ++i)
		{
			d = target - nums[i];
			if (unomap.find(d) != unomap.end() && unomap[d] > i)
			{
				result.push_back(i);
				result.push_back(unomap[d]);
				break;
			}
		}
		return result;
	}
};