77七

::以下是问题2 代码2; 把第8行中的 9 19 删除就是代码1
@echo off
setlocal enabledelayedexpansion
for /f "useback delims=" %%a in ("1.txt") do (
	set /a n+=1
	set m=%%a
)
(for %%a in (0 9 19) do (
	set /a l=n-m-%%a,k=0
	for /f "useback delims=" %%b in ("1.txt") do (
		set /a k+=1
		if !k! equ !l! echo %%b
	)
))>"2.txt"
endlocal
pause
复制代码