一、数组与双指针(Two Pointers)核心思想通过两个指针在数组中移动,降低时间复杂度(通常从 O(n²) → O(n))1. 两数之和(变种极多)经典题:Two Sum思路:哈希表记录已遍历元素时间复杂度 O(n) vector<int> twoSum(vector<int>& nums, int target) { unordered_map<int, int> mp; for (int i = 0; i < nums.size(); i++) { int diff = target - nums[i]; if (mp.count(d...