taofan712

放着我来！

@echo off
setlocal enabledelayedexpansion
for /f "tokens=1* delims=:" %%a in ('findstr /n .* 1.txt') do set num=%%a
for /f "tokens=1* delims=:" %%b in ('findstr /n .* 1.txt') do (
set str=%%c
set /a n+=1
if not "!n!"=="%num%" (
echo;!str!>>2.txt
) else (
echo;!str:~0,-2!ba>>2.txt )
)
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taofan712

此题应有更简洁的答法，mark一下，明日再战！
再 GNU前辈的指导下，代码可以缩减成这样：

@echo off&setlocal enabledelayedexpansion
for /f "tokens=1* delims=:" %%a in ('findstr /n .* 1.txt') do set "ln=%%a" &set "last=%%b"
(for /f "tokens=1* delims=:" %%a in ('findstr /n .* 1.txt') do if %%a neq %ln% (echo;%%b) else (echo;!last:~0,-2!ba ))>>2.txt
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taofan712

回复 4# Nsqs

@echo off&setlocal enabledelayedexpansion
for /f "delims=" %%a in ('findstr .* a.txt^|find /v /c ""') do set /a ln=%%a,n=1
echo;%ln%&pause
for /f "tokens=1* delims=:" %%b in ('findstr /n .* a.txt') do set last=%%c
echo;%last%&pause
for /f "tokens=1* delims=:" %%d in ('findstr /n .* a.txt') do (
if %%d neq %ln% (
set line=%%e 
echo;!line!
set /a n+=1
) else (
echo;!last:~0,-2!ba
)
)>>2.txt
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原以为我能写出更简短代码，没想到比我原答案还更多了几行。。。