Solve LeetCode 75 hash map / set problems

Author: THammami01

LeetCode-75/.vscode/launch.json

@@ -4,14 +4,14 @@
   // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
   "version": "0.2.0",
   "configurations": [
-    // {
-    //   "type": "node",
-    //   "request": "launch",
-    //   "name": "Launch Program",
-    //   "skipFiles": [
-    //     "<node_internals>/**"
-    //   ],
-    //   "program": "${workspaceFolder}\\LeetCode-75\\19-724.js"
-    // }
+    {
+      "type": "node",
+      "request": "launch",
+      "name": "Launch Program",
+      "skipFiles": [
+        "<node_internals>/**"
+      ],
+      "program": "${workspaceFolder}\\23-2352.js"
+    }
   ]
 }

LeetCode-75/20-2215.ts

@@ -0,0 +1,11 @@
+// https://leetcode.com/problems/find-the-difference-of-two-arrays/?envType=study-plan-v2&envId=leetcode-75
+
+const findDifference = (nums1: number[], nums2: number[]): number[][] => {
+  const nums1Set = new Set(nums1),
+    nums2Set = new Set(nums2);
+
+  return [
+    [...nums1Set].filter((val) => !nums2Set.has(val)),
+    [...nums2Set].filter((val) => !nums1Set.has(val)),
+  ];
+};

LeetCode-75/21-1207.ts

@@ -0,0 +1,14 @@
+// https://leetcode.com/problems/unique-number-of-occurrences/?envType=study-plan-v2&envId=leetcode-75
+
+const uniqueOccurrences = (arr) => {
+  const occurenceCountPerNb = new Map();
+
+  for (const val of arr) {
+    if (!occurenceCountPerNb.has(val)) occurenceCountPerNb.set(val, 1);
+    else occurenceCountPerNb.set(val, occurenceCountPerNb.get(val) + 1);
+  }
+
+  const occurenceCountArr = Array.from(occurenceCountPerNb.values());
+
+  return new Set(occurenceCountArr).size === occurenceCountArr.length;
+};

LeetCode-75/22-1657.ts

@@ -0,0 +1,36 @@
+// https://leetcode.com/problems/determine-if-two-strings-are-close/description/?envType=study-plan-v2&envId=leetcode-75
+
+const closeStrings = (word1: string, word2: string): boolean => {
+  if (word1.length !== word2.length) return false;
+
+  const word1LettersFrequency = new Map(),
+    word2LettersFrequency = new Map();
+
+  // O(N) SOLUTION
+  for (let i = 0; i < word1.length; i++) {
+    word1LettersFrequency.set(
+      word1[i],
+      word1LettersFrequency.has(word1[i])
+        ? word1LettersFrequency.get(word1[i]) + 1
+        : 1
+    );
+
+    word2LettersFrequency.set(
+      word2[i],
+      word2LettersFrequency.has(word2[i])
+        ? word2LettersFrequency.get(word2[i]) + 1
+        : 1
+    );
+  }
+
+  const word1Arr = [
+      ...word1LettersFrequency.keys(),
+      ...word1LettersFrequency.values(),
+    ].sort(), // NOSONAR
+    word2Arr = [
+      ...word2LettersFrequency.keys(),
+      ...word2LettersFrequency.values(),
+    ].sort(); // NOSONAR
+
+  return word1Arr.join("") === word2Arr.join("");
+};

LeetCode-75/23-2352.ts

@@ -0,0 +1,24 @@
+// https://leetcode.com/problems/equal-row-and-column-pairs/?envType=study-plan-v2&envId=leetcode-75
+
+const equalPairs = (grid: number[][]): number => {
+  if (!grid.length || !grid[0].length) return 0;
+
+  const colsMap = new Map();
+
+  for (let i = 0; i < grid.length; i++) {
+    let colStr = "";
+    for (const row of grid) colStr += row[i] + ",";
+    colStr = colStr.substring(0, colStr.length - 1);
+
+    colsMap.set(colStr, colsMap.has(colStr) ? colsMap.get(colStr) + 1 : 1);
+  }
+
+  let pairsCount = 0;
+
+  for (let row of grid) {
+    const rowStr = row.join(",");
+    if (colsMap.has(rowStr)) pairsCount += colsMap.get(rowStr);
+  }
+
+  return pairsCount;
+};

README.md

@@ -35,10 +35,10 @@
 
 ### Hash Map / Set
 
-- [ ] 20. Find the Difference of Two Arrays
-- [ ] 21. Unique Number of Occurrences
-- [ ] 22. Determine if Two Strings Are Close
-- [ ] 23. Equal Row and Column Pairs
+- [X] 20. Find the Difference of Two Arrays
+- [X] 21. Unique Number of Occurrences
+- [X] 22. Determine if Two Strings Are Close
+- [X] 23. Equal Row and Column Pairs
 
 ### Stack