153rd Commit

README.md

@@ -95,16 +95,17 @@ Ace Coding Interview with 75 Qs
 [334]: ./src/page-4/334.%20Increasing%20Triplet%20Subsequence/increasingTriplet.ts
 [443]: ./src/page-5/443.%20String%20Compression/compress.ts
 
-| Two Pointers                    |                 |        |
-| ------------------------------- | --------------- | ------ |
-| 283. Move Zeroes                | [Solution][283] | Easy   |
-| 392. Is Subsequence             | [Solution][392] | Easy   |
-| 11. Container With Most Water   | [Solution][11]  | Medium |
-| 1679. Max Number of K-Sum Pairs | Solution        | Medium |
+| Two Pointers                    |                  |        |
+| ------------------------------- | ---------------- | ------ |
+| 283. Move Zeroes                | [Solution][283]  | Easy   |
+| 392. Is Subsequence             | [Solution][392]  | Easy   |
+| 11. Container With Most Water   | [Solution][11]   | Medium |
+| 1679. Max Number of K-Sum Pairs | [Solution][1679] | Medium |
 
 [283]: ./src/page-3/283.%20Move%20Zeroes/moveZeroes.ts
 [392]: ./src/page-4/392.%20Is%20Subsequence/isSubsequence.ts
 [11]: ./src/page-1/11.%20Container%20With%20Most%20Water/maxArea.ts
+[1679]: ./src/page-16/1679.%20Max%20Number%20of%20K-Sum%20Pairs/maxOperations.ts
 
 | Sliding Window                                                |          |        |
 | ------------------------------------------------------------- | -------- | ------ |
@@ -272,7 +273,7 @@ Must-do List for Interview Prep
 | 58. Length of Last Word                                | [Solution][58]  | Easy   |
 | 14. Longest Common Prefix                              | [Solution][14]  | Easy   |
 | 151. Reverse Words in a String                         | Solution        | Medium |
-| 6. Zigzag Conversion                                   | Solution        | Medium |
+| 6. Zigzag Conversion                                   | [Solution][6]   | Medium |
 | 28. Find the Index of the First Occurrence in a String | [Solution][28]  | Easy   |
 | 68. Text Justification                                 | [Solution][68]  | Hard   |
 
@@ -283,6 +284,7 @@ Must-do List for Interview Prep
 [13]: ./src/page-1/13.%20Roman%20to%20Integer/romanToInt.ts
 [58]: ./src/page-1/58.%20Length%20of%20Last%20Word/length-of-last-word.ts
 [14]: ./src/page-1/14.%20Longest%20Common%20Prefix/longestCommonPrefix.ts
+[6]: ./src/page-1/6.%20Zigzag%20Conversion/convert.ts
 [28]: ./src/page-1/28.%20Find%20the%20Index%20of%20the%20First%20Occurrence%20in%20a%20String/strStr.ts
 [68]: ./src/page-1/68.%20Text%20Justification/fullJustify.ts
 
@@ -500,16 +502,20 @@ Must-do List for Interview Prep
 | 322. Coin Change                    | Solution       | Medium |
 | 300. Longest Increasing Subsequence | Solution       | Medium |
 
-| Multidimensional DP                      |          |        |
-| ---------------------------------------- | -------- | ------ |
-| 120. Triangle                            | Solution | Medium |
-| 64. Minimum Path Sum                     | Solution | Medium |
-| 63. Unique Paths II                      | Solution | Medium |
-| 5. Longest Palindromic Substring         | Solution | Medium |
-| 97. Interleaving String                  | Solution | Medium |
-| 72. Edit Distance                        | Solution | Medium |
-| 123. Best Time to Buy and Sell Stock III | Solution | Hard   |
-| 188. Best Time to Buy and Sell Stock IV  | Solution | Hard   |
-| 221. Maximal Square                      | Solution | Medium |
+[70]: ./src/page-1/70.%20Climbing%20Stairs/climb-stairs.ts
+
+| Multidimensional DP                      |               |        |
+| ---------------------------------------- | ------------- | ------ |
+| 120. Triangle                            | Solution      | Medium |
+| 64. Minimum Path Sum                     | Solution      | Medium |
+| 63. Unique Paths II                      | Solution      | Medium |
+| 5. Longest Palindromic Substring         | [Solution][5] | Medium |
+| 97. Interleaving String                  | Solution      | Medium |
+| 72. Edit Distance                        | Solution      | Medium |
+| 123. Best Time to Buy and Sell Stock III | Solution      | Hard   |
+| 188. Best Time to Buy and Sell Stock IV  | Solution      | Hard   |
+| 221. Maximal Square                      | Solution      | Medium |
+
+[5]: ./src/page-1/5.%20Longest%20Palindromic%20Substring/longestPalindrome.ts
 
 </details>

src/page-1/6. Zigzag Conversion/convert.test.ts

@@ -0,0 +1,9 @@
+import { convert } from './convert';
+
+describe('6. Zigzag Conversion', () => {
+  test('convert', () => {
+    expect(convert('PAYPALISHIRING', 3)).toBe('PAHNAPLSIIGYIR');
+    expect(convert('PAYPALISHIRING', 4)).toBe('PINALSIGYAHRPI');
+    expect(convert('A', 1)).toBe('A');
+  });
+});

src/page-1/6. Zigzag Conversion/convert.ts

@@ -0,0 +1,38 @@
+type Convert = (s: string, numRows: number) => string;
+
+/**
+ * Accepted
+ */
+export const convert: Convert = (s, numRows) => {
+  // No zigzag pattern if numRows is 1
+  if (numRows === 1) return s;
+
+  const rows: string[] = [];
+
+  for (let i = 0; i < Math.min(numRows, s.length); i++) {
+    rows[i] = '';
+  }
+
+  let currentRow = 0;
+  let direction = 1; // 1 means downward, -1 means upward
+
+  for (const char of s) {
+    rows[currentRow] += char;
+
+    if (currentRow === 0) {
+      direction = 1; // Change direction to downward when at the top row
+    } else if (currentRow === numRows - 1) {
+      direction = -1; // Change direction to upward when at the bottom row
+    }
+
+    currentRow += direction; // Move to the next row
+  }
+
+  let result = '';
+
+  for (const row of rows) {
+    result += row;
+  }
+
+  return result;
+};

src/page-16/1679. Max Number of K-Sum Pairs/maxOperations.test.ts

@@ -0,0 +1,8 @@
+import { maxOperations } from './maxOperations';
+
+describe('1679. Max Number of K-Sum Pairs', () => {
+  test('maxOperations', () => {
+    expect(maxOperations([1, 2, 3, 4], 5)).toBe(2);
+    expect(maxOperations([3, 1, 3, 4, 3], 6)).toBe(1);
+  });
+});

src/page-16/1679. Max Number of K-Sum Pairs/maxOperations.ts

@@ -0,0 +1,39 @@
+type MaxOperations = (nums: number[], k: number) => number;
+
+/**
+ * Accepted
+ */
+export const maxOperations: MaxOperations = (nums, k) => {
+  const numFreq = new Map<number, number>();
+
+  let count = 0;
+
+  // Count frequencies of each number in nums
+  for (const num of nums) {
+    if (!numFreq.has(num)) numFreq.set(num, 0);
+    numFreq.set(num, (numFreq.get(num) || 0) + 1);
+  }
+
+  // Iterate through nums to find pairs
+  for (const num of nums) {
+    const complement = k - num;
+    const numCount = numFreq.get(num) || 0;
+    const complementCount = numFreq.get(complement) || 0;
+
+    if (numCount > 0 && complementCount > 0) {
+      if (num === complement) {
+        // If num and complement are the same, use two of the same number
+        count += Math.floor(numCount / 2);
+        numFreq.set(num, 0);
+      } else {
+        // Otherwise, use one of each
+        const minPairs = Math.min(numCount, complementCount);
+        count += minPairs;
+        numFreq.set(num, numCount - minPairs);
+        numFreq.set(complement, complementCount - minPairs);
+      }
+    }
+  }
+
+  return count;
+};