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tech-interview-handbook
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Code Issues Projects Releases Wiki Activity

Add a ton of JS algo snippets (#56)

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pull/61/head
Yangshun Tay 7 years ago committed by GitHub
parent d8c3f984e4
commit d9b9d4b5ca
10 changed files with 136 additions and 13 deletions
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15
utilities/javascript/binToInt.js
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// Does not handle negative binary numbers.
function binToInt(binary) {
let res = 0;
for (let i = 0; i < binary.length; i++) {
res = res * 2 + (+binary[i]);
}
return res;
}
console.log(binToInt('0') === parseInt('0', 2) && parseInt('0', 2) === 0);
console.log(binToInt('1') === parseInt('1', 2) && parseInt('1', 2) === 1);
console.log(binToInt('10') === parseInt('10', 2) && parseInt('10', 2) === 2);
console.log(binToInt('11') === parseInt('11', 2) && parseInt('11', 2) === 3);
console.log(binToInt('101') === parseInt('101', 2) && parseInt('101', 2) === 5);
console.log(binToInt('1100011') === parseInt('1100011', 2) && parseInt('1100011', 2) === 99);

18
utilities/javascript/binarySearch.js
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@ -15,12 +15,12 @@ function binarySearch(arr, target) {
return -1;
}
console.log(binarySearch([1, 2, 3, 10], 1) === 0)
console.log(binarySearch([1, 2, 3, 10], 2) === 1)
console.log(binarySearch([1, 2, 3, 10], 3) === 2)
console.log(binarySearch([1, 2, 3, 10], 10) === 3)
console.log(binarySearch([1, 2, 3, 10], 9) === -1)
console.log(binarySearch([1, 2, 3, 10], 4) === -1)
console.log(binarySearch([1, 2, 3, 10], 0) === -1)
console.log(binarySearch([1, 2, 3, 10], 11) === -1)
console.log(binarySearch([5, 7, 8, 10], 3) === -1)
console.log(binarySearch([1, 2, 3, 10], 1) === 0);
console.log(binarySearch([1, 2, 3, 10], 2) === 1);
console.log(binarySearch([1, 2, 3, 10], 3) === 2);
console.log(binarySearch([1, 2, 3, 10], 10) === 3);
console.log(binarySearch([1, 2, 3, 10], 9) === -1);
console.log(binarySearch([1, 2, 3, 10], 4) === -1);
console.log(binarySearch([1, 2, 3, 10], 0) === -1);
console.log(binarySearch([1, 2, 3, 10], 11) === -1);
console.log(binarySearch([5, 7, 8, 10], 3) === -1);

5
utilities/javascript/deepEqual.js
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@ -17,9 +17,8 @@ function deepEqual(val1, val2) {
}
// Object comparison.
if (typeof val1 === 'object' && typeof val2 === 'object') {
const keys1 = Object.keys(val1);
const keys2 = Object.keys(val2);
if (typeof val1 === 'object' && typeof val2 === 'object' && val1 !== null) {
const keys1 = Object.keys(val1), keys2 = Object.keys(val2);
if (keys1.length !== keys2.length) {
return false;
}

2
utilities/javascript/graphTopoSort.js
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@ -32,4 +32,4 @@ function graphTopoSort(numberNodes, edges) {
return order.length == numberNodes ? order : [];
}
console.log(graphTopoSort(3, [[0, 1], [0, 2]]))
console.log(graphTopoSort(3, [[0, 1], [0, 2]]));

19
utilities/javascript/intToBin.js
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// Does not handle negative numbers.
function intToBin(number) {
if (number === 0) {
return '0';
}
let res = '';
while (number > 0) {
res = String(number % 2) + res;
number = parseInt(number / 2, 10);
}
return res;
}
console.log(intToBin(0) === 0..toString(2) && 0..toString(2) === '0');
console.log(intToBin(1) === 1..toString(2) && 1..toString(2) === '1');
console.log(intToBin(2) === 2..toString(2) && 2..toString(2) === '10');
console.log(intToBin(3) === 3..toString(2) && 3..toString(2) === '11');
console.log(intToBin(5) === 5..toString(2) && 5..toString(2) === '101');
console.log(intToBin(99) === 99..toString(2) && 99..toString(2) === '1100011');

17
utilities/javascript/intervalsIntersect.js
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// Interval: [start, end].
function intervalsIntersect(a, b) {
return a[0] < b[1] && b[0] < a[1];
}
console.log(intervalsIntersect([1, 2], [3, 4]) === false);
console.log(intervalsIntersect([1, 2], [2, 4]) === false);
console.log(intervalsIntersect([1, 2], [1, 4]) === true);
console.log(intervalsIntersect([1, 2], [0, 4]) === true);
console.log(intervalsIntersect([1, 2], [0, 2]) === true);
console.log(intervalsIntersect([1, 2], [0, 1.5]) === true);
console.log(intervalsIntersect([3, 4], [1, 2]) === false);
console.log(intervalsIntersect([2, 4], [1, 2]) === false);
console.log(intervalsIntersect([1, 4], [1, 2]) === true);
console.log(intervalsIntersect([0, 4], [1, 2]) === true);
console.log(intervalsIntersect([0, 2], [1, 2]) === true);
console.log(intervalsIntersect([0, 1.5], [1, 2]) === true);

16
utilities/javascript/intervalsMerge.js
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// Interval: [start, end].
// Merges two overlapping intervals into one.
function intervalsMerge(a, b) {
return [Math.min(a[0], b[0]), Math.max(a[1], b[1])];
}
const deepEqual = require('./deepEqual');
console.log(deepEqual(intervalsMerge([1, 2], [1, 4]), [1, 4]));
console.log(deepEqual(intervalsMerge([1, 2], [0, 4]), [0, 4]));
console.log(deepEqual(intervalsMerge([1, 2], [0, 2]), [0, 2]));
console.log(deepEqual(intervalsMerge([1, 2], [0, 1.5]), [0, 2]));
console.log(deepEqual(intervalsMerge([1, 4], [1, 2]), [1, 4]));
console.log(deepEqual(intervalsMerge([0, 4], [1, 2]), [0, 4]));
console.log(deepEqual(intervalsMerge([0, 2], [1, 2]), [0, 2]));
console.log(deepEqual(intervalsMerge([0, 1.5], [1, 2]), [0, 2]));

18
utilities/javascript/matrixClone.js
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function matrixClone(matrix, defaultValue) {
return matrix.map(row => {
return defaultValue === undefined ? row.slice(0) : Array(row.length).fill(defaultValue);
});
}
const deepEqual = require('./deepEqual');
// Test clone.
const a = [[1, 2], [1, 4]];
console.log(deepEqual(matrixClone(a), [[1, 2], [1, 4]]));
a[0][0] = 4;
console.log(deepEqual(matrixClone(a), [[1, 2], [1, 4]]) === false);
console.log(deepEqual(matrixClone([[1]]), [[1]]));
// Test clone with default value.
console.log(deepEqual(matrixClone([[1, 2], [1, 4]], 1), [[1, 1], [1, 1]]));
console.log(deepEqual(matrixClone([[1, 2], [1, 4]], null), [[null, null], [null, null]]));

11
utilities/javascript/matrixTranspose.js
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function matrixTranspose(matrix) {
return matrix[0].map((col, i) => matrix.map(row => row[i]));
}
const deepEqual = require('./deepEqual');
console.log(deepEqual(matrixTranspose([[1]]), [[1]]));
console.log(deepEqual(matrixTranspose([[1, 2]]), [[1], [2]]));
console.log(deepEqual(matrixTranspose([[1, 2], [1, 4]]), [[1, 1], [2, 4]]));
console.log(deepEqual(matrixTranspose([[1, 2, 3], [4, 5, 6]]), [[1, 4], [2, 5], [3, 6]]));

28
utilities/javascript/matrixTraverse.js
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function traverse(matrix) {
const DIRECTIONS = [[0, 1], [0, -1], [1, 0], [-1, 0]];
const rows = matrix.length, cols = matrix[0].length;
const visited = matrix.map(row => Array(row.length).fill(false));
function dfs(i, j) {
if (visited[i][j]) {
return;
}
visited[i][j] = true;
DIRECTIONS.forEach(dir => {
const row = i + dir[0], col = j + dir[1];
// Boundary check.
if (row < 0 || row >= rows || col < 0 || col >= cols) {
return;
}
// Valid neighbor check.
if (matrix[row][col] !== 1) {
return;
}
dfs(row, col);
});
}
for (let i = 0; i < rows; i++) {
for (let j = 0; j < cols; j++) {
dfs(i, j);
}
}
}
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