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Copy pathcycleSort.js
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62 lines (54 loc) · 1.7 KB
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/*
Wikipedia says: Cycle sort is an in-place, unstable sorting algorithm,
a comparison sort that is theoretically optimal in terms of the total
number of writes to the original array, unlike any other in-place sorting
algorithm. It is based on the idea that the permutation to be sorted can
be factored into cycles, which can individually be rotated to give a sorted result.
*/
function cycleSort(list) {
let writes = 0;
for (let cycleStart = 0; cycleStart < list.length; cycleStart++) {
let value = list[cycleStart];
let position = cycleStart;
// search position
for (let i = cycleStart+1; i < list.length; i++) {
if (list[i] < value) {
position++;
}
}
// if its the same continue
if (position == cycleStart) {
continue;
}
while (value == list[position]) {
position++;
}
let oldValue = list[position];
list[position] = value;
value = oldValue;
writes++;
// rotate the rest
while (position != cycleStart) {
position = cycleStart;
for (let i = cycleStart +1; i < list.length; i++) {
if (list[i] < value) {
position++;
}
}
while (value == list[position]) {
position++;
}
let oldValueCycle = list[position];
list[position] = value;
value = oldValueCycle;
writes++;
}
}
return writes;
}
let arrOrignal = [5, 6, 7, 8, 1, 2,12, 14];
//Array before Sort
console.log(arrOrignal);
cycleSort(arrOrignal);
//Array after sort
console.log(arrOrignal);