synthetic-intelligence · January 27, 2021 09:35 · Apr 12, 2012 · Apr 12, 2012
diff --git a/bitwise-operators.md b/bitwise-operators.md
@@ -14,7 +14,7 @@ or you will get unexpected results.
     x = x >> 1; // x = x / 2
     x = x >> 3; // x = x / 8
 
-###### Swap integers without a temporary variable
+##### Swap integers without a temporary variable
     a ^= b; // int temp = b
     b ^= a; // b = a
     a ^= b; // a = temp
@@ -23,27 +23,27 @@ or you will get unexpected results.
     i = -~i; // i++
     i = ~-i; // i--
 
-###### Sign flipping
+##### Sign flipping
     i = ~i + 1; // or
     i = (i ^ -1) + 1; // i = -i
 
 ###### Modulo operation if divisor is power of 2
     x = 131 & (4 - 1); // x = 131 % 4
 
-###### Check if an integer is even or odd
+##### Check if an integer is even or odd
     (i & 1) == 0; // (i % 2) == 0
 
 ###### Equality check
     (a^b) == 0; // a == b
 
-###### Absolute value
+##### Absolute value
     x < 0 ? -x : x; // abs(x)
     (x ^ (x >> 31)) - (x >> 31) // abs(x)
 
 ###### Equal sign check (both ints are pos or neg)
     a ^ b >= 0; // a * b > 0
 
-###### Rounding, ceiling, flooring
+##### Rounding, ceiling, flooring
     (x + 0.5) >> 0; // round(x)
     (x + 1) >> 0; // ceil(x)
     x >> 0; // floor(x)
diff --git a/bitwise-operators.md b/bitwise-operators.md
@@ -0,0 +1,49 @@
+Inspired by [this article](http://lab.polygonal.de/?p=81).
+Neat tricks for speeding up integer computations.
+
+Note: `cin.sync_with_stdio(false);` disables synchronous IO and gives you a performance boost.
+If used, you should only use `cin` for reading input
+(don't use both `cin` and `scanf` when sync is disabled, for example)
+or you will get unexpected results.
+
+##### Multiply by a power of 2
+    x = x << 1; // x = x * 2
+    x = x << 6; // x = x * 64
+
+###### Divide by a power of 2
+    x = x >> 1; // x = x / 2
+    x = x >> 3; // x = x / 8
+
+###### Swap integers without a temporary variable
+    a ^= b; // int temp = b
+    b ^= a; // b = a
+    a ^= b; // a = temp
+
+###### Increment / Decrement (slower but good for obfuscating)
+    i = -~i; // i++
+    i = ~-i; // i--
+
+###### Sign flipping
+    i = ~i + 1; // or
+    i = (i ^ -1) + 1; // i = -i
+
+###### Modulo operation if divisor is power of 2
+    x = 131 & (4 - 1); // x = 131 % 4
+
+###### Check if an integer is even or odd
+    (i & 1) == 0; // (i % 2) == 0
+
+###### Equality check
+    (a^b) == 0; // a == b
+
+###### Absolute value
+    x < 0 ? -x : x; // abs(x)
+    (x ^ (x >> 31)) - (x >> 31) // abs(x)
+
+###### Equal sign check (both ints are pos or neg)
+    a ^ b >= 0; // a * b > 0
+
+###### Rounding, ceiling, flooring
+    (x + 0.5) >> 0; // round(x)
+    (x + 1) >> 0; // ceil(x)
+    x >> 0; // floor(x)
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