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Commit 8a9d8b8

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--update: 32-bit signed int reversal
1 parent dbd3dbd commit 8a9d8b8

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2 files changed

+75
-14
lines changed

2 files changed

+75
-14
lines changed

‎src/_Problems_/reverse-number/index.js‎

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Original file line numberDiff line numberDiff line change
@@ -15,6 +15,47 @@ function reverseNumber(num) {
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return reverse * Math.sign(num);
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}
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/**
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*
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* Given a 32-bit signed integer, reverse digits of an integer.
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Example 1:
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Input: 123
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Output: 321
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Example 2:
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Input: -123
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Output: -321
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Example 3:
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Input: 1534236469
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Output: 0 // overflows
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Note:
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Assume we are dealing with an environment which could only
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store integers within the 32-bit signed integer range: [−2^31, 2^31 − 1].
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For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.
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*/
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function reverse32BitInt(x) {
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let isNegetive = 0;
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if (x < 0) {
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x *= -1;
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isNegetive = 1;
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}
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let reverse = 0;
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while (x >= 1) {
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const r = Math.floor(x % 10);
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reverse = reverse * 10 + r;
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x = Math.floor(x / 10);
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}
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if (reverse > 0x7fffffff) {
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return 0;
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}
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return isNegetive ? reverse * -1 : reverse;
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}
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module.exports = {
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reverseNumber,
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reverse32BitInt
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};
Lines changed: 34 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -1,23 +1,43 @@
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const { reverseNumber } = require('.');
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const { reverseNumber, reverse32BitInt } = require('.');
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describe('Reverse Numbers', () => {
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it('Should return a number', () => {
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expect(typeof reverseNumber(1) === 'number');
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});
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describe('Normal Reverse', () => {
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it('Should return a number', () => {
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expect(typeof reverseNumber(1) === 'number');
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});
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it('Should reverse 45 to 54', () => {
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expect(reverseNumber(45)).toEqual(54);
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});
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it('Should reverse 45 to 54', () => {
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expect(reverseNumber(45)).toEqual(54);
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});
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it('Should reverse -2 to -2', () => {
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expect(reverseNumber(-2)).toEqual(-2);
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});
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it('Should reverse -2 to -2', () => {
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expect(reverseNumber(-2)).toEqual(-2);
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});
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it('Should reverse -1234567 to -7654321', () => {
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expect(reverseNumber(-1234567)).toEqual(-7654321);
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});
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it('Should reverse -1234567 to -7654321', () => {
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expect(reverseNumber(-1234567)).toEqual(-7654321);
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it('Should throw error for invalid argument', () => {
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expect(() => reverseNumber('hello')).toThrow('Invalid Argument');
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});
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});
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it('Should throw error for invalid argument', () => {
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expect(() => reverseNumber('hello')).toThrow('Invalid Argument');
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describe('32-bit signed integer reversal', () => {
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it('Should return a number', () => {
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expect(typeof reverse32BitInt(1) === 'number');
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});
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it('Should reverse 123 to 321', () => {
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expect(reverse32BitInt(123)).toEqual(321);
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});
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it('Should reverse -871 to -178', () => {
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expect(reverse32BitInt(-871)).toEqual(-178);
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});
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it('Should return 0 for 1534236469 because of overflow when reversed', () => {
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expect(reverse32BitInt(1534236469)).toEqual(0);
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});
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});
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});

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