1- // Heap sort
1+ // https://en.wikipedia.org/wiki/Heapsort
2+ 3+ let swap = ( arr , orig , dest ) => {
4+ let temp = arr [ orig ]
5+ arr [ orig ] = arr [ dest ]
6+ arr [ dest ] = temp
7+ }
8+ 9+ let maxHeapify = ( arr , i , n ) => {
10+ let left = 2 * i + 1 ,
11+ rigth = 2 * i + 2 ,
12+ largest = i
13+ 14+ if ( left < n && arr [ left ] > arr [ i ] ) {
15+ largest = left
16+ }
17+ if ( rigth < n && arr [ rigth ] > arr [ largest ] ) {
18+ largest = rigth
19+ }
20+ if ( largest !== i ) {
21+ swap ( arr , i , largest )
22+ maxHeapify ( arr , largest , n )
23+ }
24+ }
25+ 26+ let buildMaxHeap = ( arr , n ) => {
27+ let len = Math . floor ( ( n - 1 ) / 2 )
28+ for ( let i = len ; i >= 0 ; i -- ) {
29+ maxHeapify ( arr , i , n )
30+ }
31+ }
32+ 33+ let heapSort = ( arr ) => {
34+ let n = arr . length
35+ buildMaxHeap ( arr , n )
36+ for ( let i = arr . length - 1 ; i > 0 ; i -- ) {
37+ swap ( arr , i , 0 )
38+ maxHeapify ( arr , 0 , -- n )
39+ }
40+ 41+ return arr
42+ }
43+ 44+ const test = require ( 'tape' )
45+ 46+ // test('maxHeapify', assert => {
47+ // assert.deepEqual(maxHeapify([27,17,3,16,13,10,1,5,7,12,4,8,9,0], 2),
48+ // [27,17,10,16,13,9,1,5,7,12,4,8,3,0])
49+ // assert.deepEqual(maxHeapify([16,4,10,14,7,9,3,2,8,1], 1),
50+ // [16,14,10,8,7,9,3,2,4,1])
51+ // assert.deepEqual(maxHeapify([16,14,10,8,1,9,3,2,4,7], 4),
52+ // [16,14,10,8,7,9,3,2,4,1])
53+ // assert.end()
54+ // })
55+ 56+ // test('buildMaxHeap', assert => {
57+ // assert.deepEqual(buildMaxHeap([4,1,3,2,16,9,10,14,8,7]),
58+ // [16,14,10,8,7,9,3,2,4,1])
59+ // assert.end()
60+ // })
61+ 62+ test ( 'heapSort' , assert => {
63+ assert . deepEqual ( heapSort ( [ 4 , 1 , 3 , 2 , 16 , 9 , 10 , 14 , 8 , 7 ] ) ,
64+ [ 1 , 2 , 3 , 4 , 7 , 8 , 9 , 10 , 14 , 16 ] )
65+ assert . end ( )
66+ } )
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