滑動視窗是一種技巧，用來在陣列或字串上維護一段連續的子區間。透過「右邊擴展、左邊收縮」來避免重複計算，將暴力的 O(n²) 優化到 O(n)。

Notes:

  • 視窗大小固定或可變，取決於題目條件
  • 常搭配 Hash Map 來追蹤視窗內的元素狀態
  • 關鍵在於判斷何時收縮左邊界

跨倉庫導讀#

#3 Longest Substring Without Repeating Characters #76 Minimum Window Substring #121 Best Time to Buy and Sell Stock #209 Minimum Size Subarray Sum #219 Contains Duplicate II #239 Sliding Window Maximum #424 Longest Repeating Character Replacement #567 Permutation in String #658 Find K Closest Elements #904 Fruits into Basket #1343 Number of Sub Arrays of Size K and Avg Greater than or Equal to Threshold #1456 Maximum Number of Vowels in a Substring of Given Length #1658 Minimum Operations to Reduce X to Zero #1838 Frequency of The Most Frequent Element #1888 Minimum Number of Flips to Make The Binary String Alternating