LeetCode 讀書會第 25 次聚會

紀錄/25 20210420.md

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+# LeetCode 讀書會第 25 次聚會 2021/04/20
+
+  leetcode 讀書會通知
+ 1. 項目: 第 25 次聚會
+ 2. 目的: 線上一起寫題目, 由有想法的人帶領, 先解題, 再看該題有趣的解法
+ 3. 時間: 4/20 (二) 20:00 ~ 21:00
+ 4. 地點: google meet 線上 (前 10 分鐘預備鏈接)
+ 5. 解題項目:  [Binary search](https://leetcode.com/explore/learn/card/binary-search)
+ 6. 共筆: GitHub https://github.com/programmingbookclub/Leetcode-club
+ 7. 備註: 上次有稍微聊一下 658 題目，這次會重頭開始聊658，會強調如何理解題目、題目預期的答案，與如何實作。 
+
+
+* MEDIUM	 658	 Find K Closest Elements	 https://leetcode.com/problems/find-k-closest-elements
+
+```typescript
+// `Search for a Range` in TypeScript by iteration and resursion mixed
+// Time Complexity: O(log n), Space Complexity: O(1)
+//  by louis222220 
+function searchRange(nums: number[], target: number): number[] {
+  let left = 0;
+  let right = nums.length - 1;
+  let middle: number;
+  while (left <= right) {
+    middle = getMiddleIndex(left, right);
+    if (nums[middle] === target) {
+      const leftTargerBoundary = searchLeftTargetBoundary(left, middle);
+      const rightTargetBoundary = searchRightTargetBoundary(middle, right);
+
+      const result = [leftTargerBoundary, rightTargetBoundary];
+      return result;
+    }
+    else if (nums[middle] > target) right = middle - 1;
+    else left = middle + 1;
+  }
+  return [-1, -1];
+
+  // helper functions
+  function getMiddleIndex(left: number, right: number) {
+    if (left > right) return -1;
+    if (left === right) return left;
+    return left + Math.floor((right - left) / 2);
+  }
+  /** Search left boundary of target by Recursion */
+  function searchLeftTargetBoundary(left: number, right: number) {
+    if (nums[left] === target) return left;
+    const middle = getMiddleIndex(left, right);
+
+    if (nums[middle] === target && nums[middle - 1] !== target) return middle;
+    else if (nums[middle] !== target) return searchLeftTargetBoundary(middle + 1, right);
+    else return searchLeftTargetBoundary(left, middle - 1);
+  }
+  /** Search right boundary of target by Recursion */
+  function searchRightTargetBoundary(left: number, right: number) {
+    if (nums[right] === target) return right;
+    const middle = getMiddleIndex(left, right);
+
+    if (nums[middle] === target && nums[middle + 1] !== target) return middle;
+    else if (nums[middle] !== target) return searchRightTargetBoundary(left, middle - 1);
+    else return searchRightTargetBoundary(middle + 1, right);
+  }
+};
+```
+
+* MEDIUM	 162	 Find Peak Element	 https://leetcode.com/problems/find-peak-element
+
+* Template Analysis
+
+* Article Binary Search Template Analysis
+
+* 🔓	 EASY	 270	 Closest Binary Search Tree Value	 https://leetcode.com/problems/closest-binary-search-tree-value
+
+* 🔓	 MEDIUM	 702	 Search in a Sorted Array of Unknown Size	 https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size
+
+* Conclusion
+
+* MEDIUM	 50	 Pow(x, n)	 https://leetcode.com/problems/powx-n
+
+```typescript
+/** Recursion in TS by Louis. It's inspired by [the discussion](https://leetcode.com/explore/learn/card/binary-search/137/conclusion/982/discuss/19546/Short-and-easy-to-understand-solution) */
+function myPow(x: number, n: number): number {
+  if (n == 0) return 1;
+  if (n < 0) return myPow(1 / x, -n);
+  if (n % 2 == 0) return myPow(x * x, n / 2);
+  else return x * myPow(x * x, Math.floor(n / 2));
+};
+* EASY	 367	 Valid Perfect Square	 https://leetcode.com/problems/valid-perfect-square
+
+* EASY	 744	 Find Smallest Letter Greater Than Target	 https://leetcode.com/problems/find-smallest-letter-greater-than-target
+
+* More Practices
+
+* MEDIUM	 153	 Find Minimum in Rotated Sorted Array	 https://leetcode.com/problems/find-minimum-in-rotated-sorted-array
+
+* HARD	 154	 Find Minimum in Rotated Sorted Array II	 https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii
+
+* EASY	 349	 Intersection of Two Arrays	 https://leetcode.com/problems/intersection-of-two-arrays
+
+* EASY	 350	 Intersection of Two Arrays II	 https://leetcode.com/problems/intersection-of-two-arrays-ii
+
+* EASY	 167	 Two Sum II - Input array is sorted	 https://leetcode.com/problems/two-sum-ii-input-array-is-sorted
+
+* More Practices II
+
+* MEDIUM	 287	 Find the Duplicate Number	 https://leetcode.com/problems/find-the-duplicate-number
+
+* HARD	 4	 Median of Two Sorted Arrays	 https://leetcode.com/problems/median-of-two-sorted-arrays
+
+* HARD	 719	 Find K-th Smallest Pair Distance	 https://leetcode.com/problems/find-k-th-smallest-pair-distance 
+
+* HARD	 410	 Split Array Largest Sum	 https://leetcode.com/problems/split-array-largest-sum