provide an implementation example

exercises/variable-length-quantity/example.go

@@ -2,14 +2,55 @@ package variablelengthquantity
 
 // EncodeVarint returns the varint encoding of x.
 func EncodeVarint(x uint32) []byte {
-	// TODO: implement me
-	return nil
+	if x>>7 == 0 {
+		return []byte{
+			byte(x),
+		}
+	}
+
+	if x>>14 == 0 {
+		return []byte{
+			byte(0x80 | x>>7),
+			byte(127 & x),
+		}
+	}
+
+	if x>>21 == 0 {
+		return []byte{
+			byte(0x80 | x>>14),
+			byte(0x80 | x>>7),
+			byte(127 & x),
+		}
+	}
+
+	return []byte{
+		byte(0x80 | x>>21),
+		byte(0x80 | x>>14),
+		byte(0x80 | x>>7),
+		byte(127 & x),
+	}
 }
 
 // DecodeVarint reads a varint-encoded integer from the slice.
 // It returns the integer and the number of bytes consumed, or
 // zero if there is not enough.
 func DecodeVarint(buf []byte) (x uint32, n int) {
-	// TODO: implement me
-	return 0, 0
+	if len(buf) < 1 {
+		return 0, 0
+	}
+
+	if buf[0] <= 0x80 {
+		return uint32(buf[0]), 1
+	}
+
+	var b byte
+	for n, b = range buf {
+		x = x << 7
+		x |= uint32(b) & 0x7F
+		if (b & 0x80) == 0 {
+			return x, n
+		}
+	}
+
+	return x, n
 }