Data commit

Task/Modular-inverse/Batch-File/modular-inverse.bat

@@ -0,0 +1,43 @@
+@echo off
+setlocal enabledelayedexpansion
+	%== Calls the "function" ==%
+call :ModInv 42 2017 result
+echo !result!
+call :ModInv 40 1 result
+echo !result!
+call :ModInv 52 -217 result
+echo !result!
+call :ModInv -486 217 result
+echo !result!
+call :ModInv 40 2018 result
+echo !result!
+pause>nul
+exit /b 0
+
+	%== The "function" ==%
+:ModInv
+	set a=%1
+	set b=%2
+
+	if !b! lss 0 (set /a b=-b)
+	if !a! lss 0 (set /a a=b - ^(-a %% b^))
+
+	set t=0&set nt=1&set r=!b!&set /a nr=a%%b
+
+	:while_loop
+	if !nr! neq 0 (
+		set /a q=r/nr
+		set /a tmp=nt
+		set /a nt=t - ^(q*nt^)
+		set /a t=tmp
+
+		set /a tmp=nr
+		set /a nr=r - ^(q*nr^)
+		set /a r=tmp
+		goto while_loop
+	)
+
+	if !r! gtr 1 (set %3=-1&goto :EOF)
+	if !t! lss 0 set /a t+=b
+	set %3=!t!
+	goto :EOF