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//pairing heap | |
//{elem:object, subheaps:[array of heaps]} | |
//subheaps might should be a linked list | |
function PairingHeap(obj) { | |
this.elem = obj; | |
this.subheaps = []; | |
} | |
function min(heap) { | |
return heap.elem; | |
} | |
function empty(heap) { | |
return heap.elem == null; | |
} | |
function insert(heap, obj) { | |
return merge(heap, new PairingHeap(obj)); | |
} | |
function merge(heap1, heap2) { | |
if(empty(heap1)) return heap2; | |
else if(empty(heap2)) return heap1; | |
else if(heap1.elem < heap2.elem) { | |
heap1.subheaps.push(heap2); | |
return heap1; | |
} else { | |
heap2.subheaps.push(heap1); | |
return heap2; | |
} | |
} | |
function removeMin(heap) { | |
if(empty(heap)) return null; | |
else { | |
return mergePairs(heap.subheaps); | |
} | |
} | |
function mergePairs(heaps) { | |
if(heaps.length == 0) return new PairingHeap(); | |
else if(heaps.length == 1) return heaps[0]; | |
else return merge(merge(heaps.pop(),heaps.pop()),mergePairs(heaps)); | |
} | |
function decreaseKey(heap, subheap, newValue) { | |
var newHeap = removeMin(subheap); | |
//reassign subheap values to preserve tree | |
subheap.elem = newHeap.elem; | |
subheap.subheaps = newHeap.subheaps; | |
insert(heap, newValue); | |
} |
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