remove duplication binary search symbol table code

algs4/binary_search.py

@@ -0,0 +1,52 @@
+"""
+*  Execution:    python binary_search.py whitelist.txt < input.txt
+*  Data files:   https://algs4.cs.princeton.edu/11model/tinyW.txt
+*                https://algs4.cs.princeton.edu/11model/tinyT.txt
+*                https://algs4.cs.princeton.edu/11model/largeW.txt
+*                https://algs4.cs.princeton.edu/11model/largeT.txt
+*
+* % python binary_search.py tinyW.txt < tinyT.txt
+*  50
+*  99
+*  13
+*
+* % python binary_search.py largeW.txt < largeT.txt | more
+*  499569
+*  984875
+*  295754
+*  207807
+*  140925
+*  161828
+*  [367, 966 total values]
+*
+"""
+
+
+class BinarySearch:
+    def index_of(self, arr, key):
+        lo, hi = 0, len(arr) - 1
+        while lo <= hi:
+            # key is in arr[lo..hi] or not present.
+            mid = lo + int((hi - lo) / 2)
+            if (key < arr[mid]):
+                hi = mid - 1
+            elif (key > arr[mid]):
+                lo = mid + 1
+            else:
+                return mid
+        return -1
+
+
+if __name__ == '__main__':
+    import sys
+    # read the integers from a file
+    with open(sys.argv[1]) as f:
+        whitelist = [int(i) for i in f]
+    whitelist = sorted(whitelist)
+
+    # read integer key from standard input; print if not in whitelist
+    bs = BinarySearch()
+    for line in sys.stdin:
+        key = int(line)
+        if bs.index_of(whitelist, key) == -1:
+            print(key)