1. 程式人生 > >19.1.11 LeetCode 1. Two Sum

19.1.11 LeetCode 1. Two Sum

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

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].
 1 class Solution {
 2 public:
 3     vector<int> twoSum(vector<int>& nums, int target) {
 4         map<int, int>hash;
 5         for (int i = 0; i < nums.size(); i++)
 6         {
 7             hash[target - nums[i]] = nums[i];
 8             if (hash.find(nums[i])!=hash.end()) {
9 for (int j = 0; j < i; j++) 10 if (nums[i] + nums[j] == target) 11 return vector<int>{j, i}; 12 } 13 } 14 } 15 };
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是雜湊表啊!

一開始想用排序二分,沒有想到用雜湊呢。