題目敘述：https://leetcode.com/problems/two-sum/
解題想法：Two Pointers【筆記】
- 題目要求回傳的答案是indices。使用【方法1】時需對index額外處理。不然排序後順序會亂掉。
目錄
【方法1】Two Pointers (8ms)
class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target) {
vector<pair<int,int> > check;
for (int i=0; i<nums.size(); i++){
check.push_back({nums[i], i});
}
sort(check.begin(), check.end());
vector<int> ans;
int l = 0;
int r = (int)nums.size() - 1;
while (l < r){
if (check[l].first + check[r].first > target) r--;
else if (check[l].first + check[r].first < target) l++;
else {
ans.push_back(check[l].second);
ans.push_back(check[r].second);
break;
}
}
return ans;
}
};
【方法2】暴力枚舉 (200ms)
class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target) {
int check;
vector<int> ans;
for (int i=0; i<nums.size()-1; i++){
check = target - nums[i];
for (int j=i+1; j<nums.size(); j++){
if (nums[j] == check){
ans.push_back(i);
ans.push_back(j);
}
}
if (ans.size()) break;
}
return ans;
}
};