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Pancake sort algorithm
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| // swap helper function | |
| const swap = (arr, start, end) => { | |
| let temp = arr[start]; | |
| arr[start] = arr[end]; | |
| arr[end] = temp; | |
| } | |
| // flip helper function using swap | |
| const flip = (arr, k) => { | |
| let start = 0; | |
| let end = k; | |
| while (start < end) { | |
| swap(arr, start, end); | |
| start++; | |
| end--; | |
| } | |
| } | |
| const pancakeSort = arr => { | |
| for (let i=arr.length-1; i>=0; i--) { | |
| let max = -Infinity; | |
| let maxIndex = i; | |
| let prefix = arr.slice(0, i + 1); | |
| // 1. find the index of the largest size in unsorted arr | |
| for (let j = 0; j<prefix.length; j++) { | |
| if (prefix[j] > max) { | |
| max = prefix[j]; | |
| maxIndex = j; | |
| } | |
| } | |
| // 2. flip the largest element to index 0 | |
| flip(arr, maxIndex); | |
| // 3. then flip the largest element to the sorted index | |
| flip(arr, i); | |
| } | |
| return arr; | |
| } |
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