/* Name : Fun_WheIncluded Function : 判断选定的数字是否在给定的整数中 可以知道任何一个自然数都可以拆分成若干个2的幂的和，如： 1 = 2^0 2 = 2^1 3 = 2^0 + 2^1 4 = 2^2 5 = 2^0 + 2^2 6 = 2^1 + 2^4 7 = 2^0 + 2^1 + 2^2 8 = 2^3 9 = 2^0 + 2^3 10 = 2^1 + 2^3 11 = 2^0 + 2^1 + 2^3 12 = 2^2 + 2^3 13 = 2^0 + 2^2 + 2^3 14 = 2^1 + 2^2 + 2^3 15 = 2^0 + 2^1 + 2^2 + 2^3 16 = 2^4 17 = 2^0 + 2^4 将任意一个数解析为2的幂的和的方法——递归 规律： 如给定 14 ∵ 2^3 < 14 < 2^4 ∴ 14中必有8——2^3 14 - 8 = 6 ∵ 2^2 < 6 < 2^3 ∴ 6中必有4——2^2 6 - 4 = 2 ∵ 2 = 2 ∴ 14 = 2^3 + 2^2 + 2^1
Parameters : @TotalNum Type: INT @SpecifiedNum Type: INT Steps : Author : Waxdoll Cheung Date : 2005-03-21*/
CREATE FUNCTION dbo.Fun_WheIncluded ( @TotalNum INT, @SpecifiedNum INT )RETURNS BIT AS BEGIN
DECLARE @varRet BIT
DECLARE @varLoop INT
SET @varLoop = 0
WHILE (@TotalNum >= CAST(POWER(2, @VarLoop) AS INT)) SET @varLoop = @varLoop + 1
SET @TotalNum = @TotalNum - CAST(POWER(2, @varLoop - 1) AS INT)
IF (@varLoop = @SpecifiedNum + 1) SET @varRet = 1 ELSE BEGIN IF (@TotalNum >= 1) RETURN dbo.Fun_WheIncluded(@TotalNum, @SpecifiedNum) ELSE SET @varRet = 0 END
RETURN @varRetEND
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