Updated binary_heap (keon#785)

* Corrected spelling anf grammar errors in docstring for heap.

* Fixed method signature for remove_min by removing unused parameter i.

* Fixed grammar in min_child docstring.

algorithms/heap/binary_heap.py

@@ -48,7 +48,7 @@ def perc_down(self,i):
     def min_child(self,i):
         pass
     @abstractmethod
-    def remove_min(self,i):
+    def remove_min(self):
         pass
 class BinaryHeap(AbstractHeap):
     def __init__(self):
@@ -64,8 +64,8 @@ def perc_up(self, i):
 
     """
         Method insert always start by inserting the element at the bottom.
-        it inserts rightmost spot so as to maintain the complete tree property
-        Then, it fix the tree by swapping the new element with its parent,
+        It inserts rightmost spot so as to maintain the complete tree property.
+        Then, it fixes the tree by swapping the new element with its parent,
         until it finds an appropriate spot for the element. It essentially
         perc_up the minimum element
         Complexity: O(logN)
@@ -76,7 +76,7 @@ def insert(self, val):
         self.perc_up(self.currentSize)
 
     """
-        Method min_child returns index of smaller 2 childs of its parent
+        Method min_child returns the index of smaller of 2 children of parent at index i
     """
     def min_child(self, i):
         if 2 * i + 1 > self.currentSize:  # No right child
@@ -104,7 +104,7 @@ def perc_down(self, i):
     """
     def remove_min(self):
         ret = self.heap[1]      # the smallest value at beginning
-        self.heap[1] = self.heap[self.currentSize] # Repalce it by the last value
+        self.heap[1] = self.heap[self.currentSize] # Replace it by the last value
         self.currentSize = self.currentSize - 1
         self.heap.pop()
         self.perc_down(1)