pramp-interview1: toeplitz matrix

common/utils.js

@@ -1,3 +1,5 @@
+const colors = require('colors');
+
 const isArrayEqual = (arr1, arr2) => {
     if (arr1.length !== arr2.length) return false;
 
@@ -22,7 +24,66 @@ const isArrayOfObjectsEqual = (arr1, arr2) => {
     return true;
 };
 
+
+function assert(params, result, expected, expectedResultLabel, checkType) {
+    const resultMsg = `Passed in params were ${JSON.stringify(params)} and the expected ${expectedResultLabel} is ${expected}`;
+
+    let checkCondition;
+
+    switch (checkType) {
+        case 'array':
+            checkCondition = isArrayEqual(result, expected);
+            break;
+        case 'array-of-objects':
+            checkCondition = isArrayOfObjectsEqual(result, expected);
+            break;
+        default:
+            checkCondition = result === expected;
+
+    }
+
+    if (checkCondition) {
+        console.log(resultMsg.green)
+        return true;
+    } else {
+        console.error(`${resultMsg}, found ${result}`.brightRed);
+        return false;
+    }
+}
+
+function printTestResult(solutionFunc, testData, expectedResultLabel, checkType = '') {
+    let count = 0;
+
+    testData.forEach(function loopUnitTests({ params, expectedResult, label }, index) {
+        console.log(`${index + 1}. ${label}`.yellow);
+
+        const isCorrect = assert(params, solutionFunc(params), expectedResult, expectedResultLabel, checkType);
+
+        if (!isCorrect) {
+            count += 1;
+        }
+    });
+
+    console.error(`You have ${count}/${testData.length} failling tests`.brightRed);
+    console.error(`You have ${testData.length - count}/${testData.length} passing tests. Congrats!!!`.green);
+}
+
+function printMatrix(matrix) {
+    for (let colIndex = 0; colIndex < matrix.length; colIndex++) { // iterate over columns
+        let rowString = '';
+
+        for (let rowIndex = 0; rowIndex < matrix[0].length; rowIndex++) { // iterate over rows
+            rowString += `${matrix[colIndex][rowIndex]}`;
+        }
+
+        console.log(`${rowString}`);
+    }
+    console.log('\n');
+}
+
 module.exports = {
     isArrayEqual,
-    isArrayOfObjectsEqual
+    isArrayOfObjectsEqual,
+    printTestResult,
+    printMatrix
 }

interviews/pramp/toeplitz-matrix/testData/index.js

@@ -0,0 +1,44 @@
+const testMatrixes = [
+    {
+        params: [],
+        expectedResult: false,
+        label: 'empty-array'
+    },
+    {
+        params: [[1, 2, 3, 4],
+        [5, 1, 2, 3],
+        [6, 5, 1, 2]],
+        expectedResult: true,
+        label: 'toeplitz-matrix'
+    },
+    {
+        params: [[1, 2, 3, 4],
+        [5, 1, 9, 3],
+        [6, 5, 1, 2]],
+        expectedResult: false,
+        label: 'non-toeplitz-matrix1'
+    },
+    {
+        params: [[1, 2, 3, 4],
+        [5, 1, 2, 3],
+        [6, 4, 1, 2]],
+        expectedResult: false,
+        label: 'non-toeplitz-matrix2'
+    },
+    {
+        params: [[3, 7, 0, 9, 8],
+        [5, 3, 7, 0, 9],
+        [6, 5, 3, 7, 0],
+        [4, 6, 5, 3, 7]],
+        expectedResult: true,
+        label: 'toeplitz-matrix2'
+    }, {
+        params: [[4, 0], [9, 4]],
+        expectedResult: true,
+        label: 'toeplitz-matrix3'
+    },
+];
+
+module.exports = {
+    testMatrixes,
+};

interviews/pramp/toeplitz-matrix/toeplitz-matrix.js

@@ -0,0 +1,47 @@
+const common = require('../../../common/utils.js');
+const testCases = require('./testData/index.js');
+
+/* 
+ *  Arguments:
+ *  matrix: Array[i][j] 
+ *  
+ *  0 ≤ matrix.length ≤ 20
+ *  0 ≤ matrix[i].length ≤ 20
+ *  0 ≤ matrix[i][j] ≤ 20
+ * NB: matrix is not necessarily square, i.e. with the same number of columns and rows
+ * 
+ * returns boolean if matrix is of type Toeplitz, i.e. has the same number on its descending diagonal from left to rigth
+ * 
+ * eg. 
+ * const matrix = [[1,2,3,4],
+ *                 [5,1,2,3],
+ *                 [6,5,1,2]];
+ * isToeplitzMatrix(matrix) 
+ * returns true
+ * 
+ * const matrix = [[1,2,3,4],
+ *                 [5,1,9,3],
+ *                 [6,5,1,2]];
+ * 
+ * isToeplitzMatrix(matrix) 
+ * returns false
+*/
+
+function isToeplitzMatrix(matrix = []) {
+    const diagonalStart = matrix[0] && matrix[0][0] || '';
+
+    if (!diagonalStart) return false;
+
+    for (let i = 0; i < matrix.length - 1; i++) { // iterate over rows
+        for (let j = 0; j < matrix[0].length - 1; j++) { // iterate over columns
+            if (matrix[i][j] !== matrix[i + 1][j + 1]) {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+
+common.printTestResult(isToeplitzMatrix, testCases.testMatrixes, 'result to the question is it a toeplitz matrix ?');