Created
November 4, 2018 09:05
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public int parent(int i) { | |
return (i-1)/2; | |
} | |
public int left(int i) { | |
return i*2+1; | |
} | |
public int right(int i) { | |
return left(i)+1; | |
} | |
public void maxHeapify(int[] arr, int i, int length) { | |
if (length == 0) return; | |
int hv = arr[i]; | |
int l = left(i); | |
int r = right(i); | |
int max = hv; | |
int ti = i; | |
if (l < length && arr[l] > arr[ti]) ti = l; | |
if (r < length && arr[r] > arr[ti]) ti = r; | |
if (ti != i) { | |
swap(arr, ti, i); | |
maxHeapify(arr, ti); | |
} | |
} | |
public void buildMaxHeap(int[] arr) { | |
if (arr.length == 0) return; | |
for (int i = parent(arr.length-1); i>=0; i--) { | |
maxHeapify(arr, i, arr.length); | |
} | |
} | |
public void heapSort(int[] arr) { | |
if (arr.length == 0) return; | |
buildMaxHeap(arr); | |
for (int i = arr.length-1; i>=0; i--) { | |
swap(i, 0); | |
maxHeapify(arr, 0, i); | |
} | |
} |
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