diff --git a/Data Structures/Heap/MinPriorityQueue.js b/Data Structures/Heap/MinPriorityQueue.js new file mode 100644 index 000000000..3da161756 --- /dev/null +++ b/Data Structures/Heap/MinPriorityQueue.js @@ -0,0 +1,128 @@ + +/* Minimum Priority Queue +* It is a part of heap data structure +* A heap is a specific tree based data structure +* in which all the nodes of tree are in a specific order. +* that is the children are arranged in some +* respect of their parents, can either be greater +* or less than the parent. This makes it a min priority queue +* or max priority queue. +*/ + +// Functions: insert, delete, peek, isEmpty, print, heapSort, sink + +class MinPriorityQueue { + + // calss the constructor and initializes the capacity + constructor(c) { + this.heap = []; + this.capacity = c; + this.size = 0; + } + + // inserts the key at the end and rearranges it + // so that the binary heap is in appropriate order + insert(key) { + if (this.isFull()) return; + this.heap[this.size + 1] = key; + let k = this.size + 1; + while (k > 1) { + if (this.heap[k] < this.heap[Math.floor(k / 2)]) { + let temp = this.heap[k]; + this.heap[k] = this.heap[Math.floor(k / 2)]; + this.heap[Math.floor(k / 2)] = temp; + } + k = Math.floor(k / 2); + } + this.size++; + } + + // returns the highest priority value + peek() { + return this.heap[1]; + } + + // returns boolean value whether the heap is empty or not + isEmpty() { + if (0 == this.size) return true; + return false; + } + + // returns boolean value whether the heap is full or not + isFull() { + if (this.size == this.capacity) return true; + return false; + } + + // prints the heap + print() { + console.log(this.heap.slice(1)); + } + + // heap sorting can be done by performing + // delete function to the number of times of the size of the heap + // it returns reverse sort because it is a min priority queue + heapSort() { + for (let i = 1; i < this.capacity; i++) { + this.delete(); + } + } + + // this function reorders the heap after every delete function + sink() { + let k = 1; + while (2 * k <= this.size || 2 * k + 1 <= this.size) { + let minIndex; + if (this.heap[2 * k] >= this.heap[k]) { + if (2 * k + 1 <= this.size && this.heap[2*k+1] >= this.heap[k]) { + break; + } + else if(2*k+1 > this.size){ + break; + } + } + if (2 * k + 1 > this.size) { + minIndex = this.heap[2 * k] < this.heap[k] ? 2 * k : k; + } else { + if ( + this.heap[k] > this.heap[2 * k] || + this.heap[k] > this.heap[2 * k + 1] + ) { + minIndex = + this.heap[2 * k] < this.heap[2 * k + 1] ? 2 * k : 2 * k + 1; + } else { + minIndex = k; + } + } + let temp = this.heap[k]; + this.heap[k] = this.heap[minIndex]; + this.heap[minIndex] = temp; + k = minIndex; + } + } + + // deletes the highest priority value from the heap + delete() { + let min = this.heap[1]; + this.heap[1] = this.heap[this.size]; + this.heap[this.size] = min; + this.size--; + this.sink(); + return min; + } +} + +// testing +q = new MinPriorityQueue(8); + +q.insert(5); +q.insert(2); +q.insert(4); +q.insert(1); +q.insert(7); +q.insert(6); +q.insert(3); +q.insert(8); +q.print(); // [ 1, 2, 3, 5, 7, 6, 4, 8 ] +q.heapSort(); +q.print(); // [ 8, 7, 6, 5, 4, 3, 2, 1 ]