From 85d2f180afef66d36890696edeb838e0a47e3009 Mon Sep 17 00:00:00 2001
From: KamillaKhabibrakhmanova <venessiel@gmail.com>
Date: Tue, 26 Jul 2016 20:52:13 -0400
Subject: [PATCH] added basic sorting algorithms

---
 .../3.5-QueueWithTwoStacks.js                 | 26 ++++++++++
 Sorting/SelectionSort.js                      | 12 +++++
 Sorting/heapSort.js                           | 48 +++++++++++++++++++
 Sorting/mergeSort.js                          | 23 +++++++++
 Sorting/quicksort.js                          | 37 ++++++++++++++
 5 files changed, 146 insertions(+)
 create mode 100644 Chapter3-StacksandQueues/3.5-QueueWithTwoStacks.js
 create mode 100644 Sorting/SelectionSort.js
 create mode 100644 Sorting/heapSort.js
 create mode 100644 Sorting/mergeSort.js
 create mode 100644 Sorting/quicksort.js

diff --git a/Chapter3-StacksandQueues/3.5-QueueWithTwoStacks.js b/Chapter3-StacksandQueues/3.5-QueueWithTwoStacks.js
new file mode 100644
index 0000000..cad2971
--- /dev/null
+++ b/Chapter3-StacksandQueues/3.5-QueueWithTwoStacks.js
@@ -0,0 +1,26 @@
+/*
+Problem: Impletement a MyQueue class which implements a queue using two stacks
+*/
+
+var MyQueue = function(){
+	this.current = [];
+	this.empty = [];
+};
+
+MyQueue.prototype.enqueue = function(val){
+	this.current.push(val);
+};
+//runtime O(1)
+
+MyQueue.prototype.dequeue = function(){
+	var currentVal;
+	while (this.current.length > 1) {
+		this.empty.push(this.current.pop());
+	}
+	var result = this.current.pop();
+	while (this.empty.length > 0) {
+		this.current.push(this.empty.pop());
+	}
+	return result;
+};
+//runtime O(n)
\ No newline at end of file
diff --git a/Sorting/SelectionSort.js b/Sorting/SelectionSort.js
new file mode 100644
index 0000000..ab6b8ac
--- /dev/null
+++ b/Sorting/SelectionSort.js
@@ -0,0 +1,12 @@
+function selectionSort(array) {
+	for (var i = 0; i < array.length; i++) {
+		var min = i;
+		for (var k = i + 1; k < array.length; k++) {
+			if (array[k] < array[min]) min = k;
+		}
+		var temp = array[i];
+		array[i] = array[min];
+		array[min] = temp;
+	}
+	return array;
+}
\ No newline at end of file
diff --git a/Sorting/heapSort.js b/Sorting/heapSort.js
new file mode 100644
index 0000000..8e38014
--- /dev/null
+++ b/Sorting/heapSort.js
@@ -0,0 +1,48 @@
+var Heap = function(){
+	this.heap = [];
+}
+
+Heap.prototype.insert = function(data) {
+	if (!this.heap.length) {
+		this.heap.push(data);
+	}
+	else {
+		var i = this.heap.length;
+		var parent = Math.floor(i/2);
+		this.heap[i] = data;
+		while (data > this.heap[Math.floor(i/2)] && i > 0){
+			var temp = this.heap[Math.floor(i/2)];
+			this.heap[ Math.floor(i/2)] = data;
+			this.heap[i] = temp;
+			i = Math.floor(i/2);
+		}
+	}
+};
+
+Heap.prototype.remove = function(){
+	var maximum = this.heap[0];
+	var n = this.heap.pop();
+	if (n === maximum) return n;
+	this.heap[0] = n;
+	var i = 0;
+	while (n < this.heap[2*i + 1] || n < this.heap[2*i + 2]){
+		var largest = this.heap[2*i +1] > (this.heap[2 * i + 2] || 0) ? 2*i + 1 : 2*i + 2;
+		this.heap[i] = this.heap[largest];
+		this.heap[largest] = n;
+		i = largest;
+	}
+	return maximum;
+};
+
+function heapSort(array) {
+	var heap = new Heap();
+	var result = [];
+	while (array.length > 0) {
+		var n = array.pop();
+		heap.insert(n);
+	}
+	while (heap.heap.length > 0) {
+		result.push(heap.remove());
+	}
+	return result;
+}
\ No newline at end of file
diff --git a/Sorting/mergeSort.js b/Sorting/mergeSort.js
new file mode 100644
index 0000000..071d181
--- /dev/null
+++ b/Sorting/mergeSort.js
@@ -0,0 +1,23 @@
+function mergeSort(array) {
+	if (array.length === 1 || array.length === 0) return array;
+	else {
+		var midpoint = Math.floor(array.length / 2);
+		return merge(mergeSort(array.slice(0, midpoint)), mergeSort(array.slice(midpoint, array.length)));
+	}
+}
+
+function merge(array1, array2) {
+	var result = [];
+	var i = 0;
+	var j = 0;
+	while (i < array1.length || j < array2.length) {
+		if (array1[i] >= (array2[j] || 0)) {
+			result.push(array1[i]);
+			i++;
+		} else if (array2[j] > (array1[i] ||0)) {
+			result.push(array2[j]);
+			j++;
+		}
+	}
+	return result;
+}
\ No newline at end of file
diff --git a/Sorting/quicksort.js b/Sorting/quicksort.js
new file mode 100644
index 0000000..831531a
--- /dev/null
+++ b/Sorting/quicksort.js
@@ -0,0 +1,37 @@
+var partition = function(array, left, right) {
+	var midpoint = Math.ceil((right + left)/2);
+	var pivot = array[midpoint];
+	while (left < right) {
+		while (array[left] < pivot) {
+			left ++;
+		}
+		
+		while (array[right] > pivot) {
+			right --;
+		}
+		if (left < right ) {
+
+			swap(array, left, right);
+		}
+	}
+	return left;
+};
+
+var swap = function(array, index1, index2) {
+	var temp = array[index1];
+	array[index1] = array[index2];
+	array[index2] = temp;
+};
+
+var quickSort = function(array, left, right) {
+	if (!left) left = 0;
+	if (!right) right = array.length - 1;
+	var pivot = partition(array, left, right);
+	if (left < pivot - 1) {
+		quickSort(array, left, pivot -1 );
+	}
+	if (right > pivot + 1) {
+		quickSort(array, pivot, right);
+	}
+	return array;
+};
\ No newline at end of file