sort and search algorithm added

Searching Algorithm/binary_search.py

@@ -0,0 +1,29 @@
+#
+# Binary search works for a sorted array.
+# Note: The code logic is written for an array sorted in
+#       increasing order.
+# T(n): O(log n)
+#
+def binary_search(array, query):
+    lo, hi = 0, len(array) - 1
+    while lo <= hi:
+        mid = (hi + lo) // 2
+        val = array[mid]
+        if val == query:
+            return mid
+        elif val < query:
+            lo = mid + 1
+        else:
+            hi = mid - 1
+    return None
+
+def binary_search_recur(array, low, high, val):
+    if low > high:       # error case
+        return -1
+    mid = (low + high) // 2
+    if val < array[mid]:
+        return binary_search_recur(array, low, mid - 1, val)
+    elif val > array[mid]:
+        return binary_search_recur(array, mid + 1, high, val)
+    else:
+        return mid

Sorting Algorithm/bfs.py

@@ -0,0 +1,27 @@
+def bfs(graph, start):
+    """
+    return the set of all nodes that can be visited in the graph from start node
+    """
+    visited = set()
+    queue = [start]
+    while queue:
+        current = queue.pop(0)
+        if current not in visited:
+            visited.add(current)
+            queue.extend(graph[current] - visited)
+    return visited
+
+def bfs_path(graph, start, end):
+    """
+    return if there is a possible path from start node to end node in the graph
+    """
+    visited = set()
+    queue = [start]
+    while queue:
+        current = queue.pop(0)
+        if current not in visited:
+            if current == end:
+                return True
+            visited.add(current)
+            queue.extend(graph[current] - visited)
+    return False