|
6 | 6 | </a>
|
7 | 7 | </p>
|
8 | 8 |
|
| 9 | +<p align="center"> |
| 10 | + <a href="https://youtu.be/4n90F6PCQ6A"> |
| 11 | + <img src="https://img.youtube.com/vi/4n90F6PCQ6A/0.jpg" alt="Sorting In JavaScript" /> |
| 12 | + </a> |
| 13 | +</p> |
| 14 | + |
9 | 15 | ### Sort an Array
|
10 | 16 | ```javascript
|
11 | 17 | const arr = [-2, -7, 1000, 5]
|
@@ -76,4 +82,127 @@ const insertionSort = (arr) => {
|
76 | 82 | }
|
77 | 83 |
|
78 | 84 | console.log(insertionSort(arr)) // -7, -2 , 5, 1000
|
79 |
| -``` |
| 85 | +``` |
| 86 | + |
| 87 | +### Merge Sort in JavaScript |
| 88 | +```javascript |
| 89 | +const mergeSort = (arr) => { |
| 90 | + if (arr.length < 2) { |
| 91 | + return arr; |
| 92 | + } |
| 93 | + let mid = Math.floor(arr.length / 2); |
| 94 | + let left = mergeSort(arr.slice(0, mid)) |
| 95 | + let right = mergeSort(arr.slice(mid)) |
| 96 | + return merge(left, right) |
| 97 | +} |
| 98 | + |
| 99 | +const merge = (left, right) => { |
| 100 | + const result = [] |
| 101 | + let leftIndex = 0, rightIndex = 0; |
| 102 | + while (leftIndex < left.length && rightIndex < right.length) { |
| 103 | + if (left[leftIndex] < right[rightIndex]) { |
| 104 | + result.push(left[leftIndex]) |
| 105 | + leftIndex++; |
| 106 | + } |
| 107 | + else { |
| 108 | + result.push(right[rightIndex]) |
| 109 | + rightIndex++; |
| 110 | + } |
| 111 | + } |
| 112 | + |
| 113 | + while (leftIndex < left.length) { |
| 114 | + result.push(left[leftIndex]) |
| 115 | + leftIndex++; |
| 116 | + } |
| 117 | + |
| 118 | + while (rightIndex < right.length) { |
| 119 | + result.push(right[rightIndex]) |
| 120 | + rightIndex++; |
| 121 | + } |
| 122 | + |
| 123 | + return result; |
| 124 | +} |
| 125 | + |
| 126 | +const arr1 = [29, 10, 8, 16, 37, 14, 4, 45] |
| 127 | +console.log(mergeSort(arr1)) |
| 128 | +``` |
| 129 | +### Merge Sort in JavaScript (Space Optimised) |
| 130 | + |
| 131 | +```javascript |
| 132 | +const mergeSortInplace = (arr, low, high) => { |
| 133 | + if (low < high) { |
| 134 | + let mid = Math.floor((low + high) / 2); |
| 135 | + mergeSortInplace(arr, low, mid) |
| 136 | + mergeSortInplace(arr, mid + 1, high) |
| 137 | + mergeInplace(arr, low, mid, high) |
| 138 | + } |
| 139 | +} |
| 140 | + |
| 141 | +const mergeInplace = (arr, low, mid, high) => { |
| 142 | + const result = [] |
| 143 | + let leftIndex = low, rightIndex = mid + 1; |
| 144 | + while (leftIndex <= mid && rightIndex <= high) { |
| 145 | + if (arr[leftIndex] < arr[rightIndex]) { |
| 146 | + result.push(arr[leftIndex]) |
| 147 | + leftIndex++; |
| 148 | + } |
| 149 | + else { |
| 150 | + result.push(arr[rightIndex]) |
| 151 | + rightIndex++; |
| 152 | + } |
| 153 | + } |
| 154 | + |
| 155 | + while (leftIndex <= mid) { |
| 156 | + result.push(arr[leftIndex]) |
| 157 | + leftIndex++; |
| 158 | + } |
| 159 | + |
| 160 | + while (rightIndex <= high) { |
| 161 | + result.push(arr[rightIndex]) |
| 162 | + rightIndex++; |
| 163 | + } |
| 164 | + |
| 165 | + for (let i = low; i <= high; i++) { |
| 166 | + arr[i] = result[i - low]; |
| 167 | + } |
| 168 | +} |
| 169 | + |
| 170 | +const arr1 = [29, 10, 8, 16, 37, 14, 4, 45] |
| 171 | +console.log(mergeSortInplace(arr1, 0, arr.length - 1)) |
| 172 | +console.log(arr1) |
| 173 | +``` |
| 174 | + |
| 175 | +### Quick Sort in JavaScript |
| 176 | + |
| 177 | +```javascript |
| 178 | +const quickSort = (arr) => { |
| 179 | + if(arr.length < 2){ |
| 180 | + return arr; |
| 181 | + } |
| 182 | + let pivotIndex = Math.floor(Math.random() * arr.length); |
| 183 | + let left = [], right = []; |
| 184 | + for(let i=0; i<arr.length; i++){ |
| 185 | + if(i === pivotIndex) |
| 186 | + continue; |
| 187 | + |
| 188 | + if(arr[i] < arr[pivotIndex]){ |
| 189 | + left.push(arr[i]) |
| 190 | + } |
| 191 | + else{ |
| 192 | + right.push(arr[i]) |
| 193 | + } |
| 194 | + } |
| 195 | + |
| 196 | + return [...quickSort(left), arr[pivotIndex], ...quickSort(right)] |
| 197 | +} |
| 198 | + |
| 199 | +console.log(quickSort(arr1)) |
| 200 | +``` |
| 201 | + |
| 202 | +## Practice Question |
| 203 | + |
| 204 | +- [How Many Numbers are smaller than the current number](https://leetcode.com/problems/how-many-numbers-are-smaller-than-the-current-number) |
| 205 | +- [Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array) |
| 206 | +- [Sort an Array](https://leetcode.com/problems/sort-an-array) |
| 207 | +- [Largest Number](https://leetcode.com/problems/largest-number) |
| 208 | +- [Sort Color](https://leetcode.com/problems/sort-colors) |
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