Add: Exercise 2352. Equal Row and Column Pairs

Author: BlackBeast593

2352-equal-row-and-column-pairs/README.md

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+# 2352. Equal Row and Column Pairs
+Given a 0-indexed `n x n` integer matrix `grid`, return the number of pairs `(ri, cj)` such that row
+`ri` and column `cj` are equal.
+
+A row and column pair is considered equal if they contain the same elements in the same order (i.e.,
+an equal array).
+
+## Examples
+
+### Example 1:
+
+Input: `grid` = [[3,2,1],[1,7,6],[2,7,7]]  
+Output: 1  
+Explanation: There is 1 equal row and column pair:  
+- (Row 2, Column 1): [2,7,7]
+
+### Example 2:
+
+Input: `grid` = [[3,1,2,2],[1,4,4,5],[2,4,2,2],[2,4,2,2]]  
+Output: 3  
+Explanation: There are 3 equal row and column pairs:  
+- (Row 0, Column 0): [3,1,2,2]  
+- (Row 2, Column 2): [2,4,2,2]  
+- (Row 3, Column 2): [2,4,2,2]
+
+## Constraints
+
+- `n == grid.length == grid[i].length`
+- `1 <= n <= 200`
+- `1 <= grid[i][j] <= 10^5`

2352-equal-row-and-column-pairs/index.js

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+/**
+ * Counts the number of equal row-column pairs in a square matrix.
+ * @param {number[][]} grid - The input square matrix.
+ * @return {number} - The number of equal row-column pairs.
+ */
+var equalPairs = function(grid) {
+    // Check that it's an square matrix
+    if (grid.length !== grid[0].length) return 0
+
+    // Initialize variables
+    const rows = {}
+    const columns = {}
+    let equalPairsCount = 0
+
+    // Populate the `rows` object, convert row contents to string for further comparison
+    for (let i = 0; i < grid.length; i++) {
+        rows[i] = grid[i].join()
+    }
+
+    // Populate the `columns` object, convert columns to string
+    for (let i = 0; i < grid.length; i++) {
+        for (let j = 0; j < grid.length; j++) {
+            // We'll use commas to help us distinguish between columns and rows with similar
+            // characters. For example if row = [11,1] and column = [1,11] are compare as strings,
+            // without commas, the comparison will be '111' === '111' which will cause a false
+            // positive
+            columns[j] ? 
+                columns[j] = columns[j] + ',' + grid[i][j].toString() :
+                columns[j] = '' + grid[i][j].toString()
+        }
+    }
+
+    // Compare rows with columns and increment the pair counter
+    for (const row in rows) {
+        for(const column in columns) {
+            if (rows[row] === columns[column]) {
+                equalPairsCount++
+            }
+        }
+    }
+
+    return equalPairsCount
+};
+
+const grid = [[3,2,1],[1,7,6],[2,7,7]]
+var output = equalPairs(grid)
+
+module.exports = equalPairs

2352-equal-row-and-column-pairs/package.json

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+{
+  "name": "2352-equal-row-and-column-pairs",
+  "version": "1.0.0",
+  "description": "Given a 0-indexed `n x n` integer matrix `grid`, return the number of pairs `(ri, cj)` such that row `ri` and column `cj` are equal.",
+  "main": "index.js",
+  "scripts": {
+    "start": "node index.js",
+    "debug": "node --inspect-brk index.js",
+    "test": "node test.js"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC"
+}

2352-equal-row-and-column-pairs/test.js

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+const assert = require('assert')
+const equalPairs = require('./index')
+
+const tests = [
+    {
+        grid: [[3,2,1],[1,7,6],[2,7,7]],
+        expectedOutput: 1
+    },
+    {
+        grid: [[3,1,2,2],[1,4,4,5],[2,4,2,2],[2,4,2,2]],
+        expectedOutput: 3,
+    },
+    {
+        grid: [[11,1],[1,11]],
+        expectedOutput: 2,
+    },
+]
+
+for (const t of tests) {
+    assert.strict.strictEqual(equalPairs(t.grid), t.expectedOutput)
+}