68 lines
1.6 KiB
Markdown
68 lines
1.6 KiB
Markdown
## 题目地址
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https://leetcode-cn.com/problems/two-sum/
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## 思路
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## 一般解法
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代码：
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```C++
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```
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## 优化解法
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```C++
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class Solution {
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public:
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vector<int> twoSum(vector<int>& nums, int target) {
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for (int i = 0; i < nums.size(); i ++) {
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for (int j = i + 1; j < nums.size(); j++) {
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if (nums[i] + nums[j] == target) {
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return {i, j};
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}
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}
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}
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return {};
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}
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};
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```
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```
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class Solution {
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public:
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vector<int> twoSum(vector<int>& nums, int target) {
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std::map <int,int> map;
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for(int i = 0; i < nums.size(); i++) {
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auto iter = map.find(target - nums[i]);
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if(iter != map.end()) {
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return {iter->second,i};
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}
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map.insert({nums, i});
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}
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return {};
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}
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};
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```
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```
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class Solution {
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public:
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vector<int> twoSum(vector<int>& nums, int target) {
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std::unordered_map <int,int> map;
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for(int i = 0; i < nums.size(); i++) {
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auto iter = map.find(target - nums[i]);
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if(iter != map.end()) {
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return {iter->second, i};
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break;
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}
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map.emplace(nums[i], i);
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}
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return {};
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}
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};
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```
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