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Commit 4d8d0b8

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implamenting ternary search
1 parent 9b6f8f5 commit 4d8d0b8

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2 files changed

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2 files changed

+94
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Lines changed: 41 additions & 0 deletions
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const { ternarySearch, ternarySearchRecursive } = require('.');
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describe('Ternary Search', () => {
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const array = [1, 2, 3, 4, 5, 6, 7, 8];
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const low = 0;
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const high = array.length - 1;
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describe('When element to find is at 1st position ', () => {
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it('Ternary search with Loop', () => {
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expect(ternarySearch(array, 1)).toEqual(0);
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});
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it('Ternary serach with recursion', () => {
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expect(ternarySearchRecursive(array, low, high, 1)).toEqual(0);
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});
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});
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describe('When element to find is at last position ', () => {
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it('Ternary search with Loop', () => {
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expect(ternarySearch(array, 7)).toEqual(6);
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});
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it('Ternary serach with recursion', () => {
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expect(ternarySearchRecursive(array, low, high, 7)).toEqual(6);
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});
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});
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describe('When element to find is at random position ', () => {
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it('Ternary search with Loop', () => {
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expect(ternarySearch(array, 3)).toEqual(2);
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});
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it('Ternary serach with recursion', () => {
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expect(ternarySearchRecursive(array, low, high, 3)).toEqual(2);
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});
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});
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describe('When element to find is no present in array ', () => {
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it('Ternary search with Loop', () => {
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expect(ternarySearch(array, 10)).toEqual(null);
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});
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it('Ternary serach with recursion', () => {
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expect(ternarySearchRecursive(array, low, high, 10)).toEqual(null);
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});
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});
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});
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/**
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* Note: Array must be sorted for binary search
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*/
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function ternarySearch(arr, key){
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let left = 0;
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let right = arr.length - 1;
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while(left <= right){
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let temp2 = left + Math.floor((right - left) / 3);
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let temp3 = left + 2 * Math.floor((right - left) / 3);
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if(key == arr[left]){
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return left;
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} else if(key == arr[right]){
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return right;
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} else if(key < arr[left] || key > arr[right]){
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return null;
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} else if(key <= arr[temp2]){
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right = temp2;
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} else if(key > arr[temp2] && key <= arr[temp3]){
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left = temp2 + 1;
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right = temp3;
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} else {
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left = temp3 + 1;
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}
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}
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return null;
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}
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function ternarySearchRecursive(arr, low, high, key){
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if(high >= low){
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let highMiddle = low + 2 * Math.floor((high - low) / 3);
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let lowMiddle = low + Math.floor((high - low) / 3);
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if(key === arr[lowMiddle]){
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return lowMiddle;
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} else if(key === arr[highMiddle]){
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return highMiddle;
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} else if(key < arr[highMiddle]){
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return ternarySearchRecursive(arr, low, lowMiddle, key);
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} else if(key > arr[lowMiddle] && key < arr[highMiddle]){
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return ternarySearchRecursive(arr, lowMiddle, highMiddle, key);
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} else if(arr.indexOf(key) == - 1){
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return null;
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} else {
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return ternarySearchRecursive(arr, highMiddle, high, key);
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}
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}
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return null;
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}
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module.exports = {
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ternarySearch,
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ternarySearchRecursive
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};

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