QBasic 计算还须要净胜/负多少局才能胜率增/减1%

2014年的12月29日，写了个VBS脚本，计算还须要连胜多少把才能让本身的胜率提高1%：

这个脚本的地址在：http://my.oschina.net/Tsybius2014/blog/362078

结果后来连着输了几把，胜率掉了1%（汗）。正好昨天看了下QBasic，就用QBasic写段代码计算一下吧

个人编码环境为：编译器为Win32下的FreeBasic（版本1.00.0），IDE为FBIde（版本0.4.6r4）

这段代码计算了还须要连胜多少把才能把本身的胜率提高1%，也计算了还须要连败多少把就会让胜率下降1%

计算规则：

1）以当前玩了426局，获胜86局为例，当前的胜率是0.201878，截去小数后是20%。

2）在这个基础上，连胜4局后，玩了430局，获胜90局，胜率为0.209302，截去小数后仍是20%；但在连胜5局后，玩了431局，获胜91局，胜率到达0.211137，截去小数后胜率到达21%！这个时候，就认为是连胜5局后，就能够让胜率增长1个百分点。

3）同理，计算负场时，连负4局后，玩了430局，获胜86局，胜率为0.2，即20%；连负5局后，玩了431局，获胜86局，胜率为0.199536，截去小数后，是19%，视为胜率降低一个百分点。

须要注意的几点是：

1）胜率100%的时候，再连胜多少局胜率都是100%

2）胜率99%的时候，再连胜多少局胜率都是99%

3）胜率0%的时候，再连负多少局胜率都是0%

程序代码以下：

REM 计算还须要连胜多少局才能让胜率涨一点
REM 计算还须要连败多少局才能让胜率降一点

DIM GAMEPLAYED AS INTEGER 
DIM GAMEWON AS INTEGER  

DIM INPUT1 AS STRING : INPUT "HOW MANY GAMES HAVE YOU PLAYED? "; INPUT1
DIM INPUT2 AS STRING : INPUT "HOW MANY GAMES HAVE YOU WON? "; INPUT2

PRINT

GAMEPLAYED = FIX(VAL(INPUT1))
GAMEWON = FIX(VAL(INPUT2))

PRINT "GAMEPLAYED: "; GAMEPLAYED
PRINT "GAMEWON: "; GAMEWON

PRINT

'输入合法性校验
IF GAMEPLAYED < 0 OR GAMEWON < 0 OR GAMEPLAYED < GAMEWON THEN
    PRINT "GAMEPLAYED MUST BIGGER-EQUAL THAN 0"
    PRINT "GAMEWON MUST BIGGER-EQUAL THAN 0"
    PRINT "GAMEPLAYED MUST BIGGER THAN GAMEWON"
    GOTO PRG_FINISH 
END IF

'计算当前胜率
PRINT "CURRENT WINNING RATE: "; GAMEWON * 100 \ GAMEPLAYED; "%"

'计数器
DIM COUNTER AS INTEGER

'计算还须要多少局连胜才能增加一点胜率

'检查特例
IF GAMEPLAYED = GAMEWON THEN
    PRINT "NO NEED TO IMPROVE!"
    GOTO MISSION1_COMPLETE
ELSEIF GAMEWON * 100 \ GAMEPLAYED = 99 THEN
    PRINT "NO SOLUTION TO IMPROVE!"
    GOTO MISSION1_COMPLETE
END IF

'模拟玩一局赢一局的过程
COUNTER = 1
DO 
    IF (GAMEWON + COUNTER - 1) * 100 \ (GAMEPLAYED + COUNTER - 1) < _
        (GAMEWON + COUNTER) *  100 \ (GAMEPLAYED + COUNTER) THEN
        EXIT DO
    ELSE
        COUNTER = COUNTER + 1
    END IF
LOOP

'打印结论1
PRINT "TO IMPROVE 1% WINNING RATE, YOU NEED TO WIN"; COUNTER; " GAME(S) CONTINUOUSLY"

MISSION1_COMPLETE:

'计算还须要多少局连败才能下降一点胜率

'检查特例
IF GAMEWON = 0 THEN
    PRINT "WINNING PERCENTAGE: 0%"
    PRINT "CANNOT DECLINE ANY MORE!"
    GOTO MISSION2_COMPLETE
END IF

'模拟玩一局输一局的过程
COUNTER = 1
DO 
    IF (GAMEWON) * 100 \ (GAMEPLAYED + COUNTER - 1) > _
        (GAMEWON) *  100 \ (GAMEPLAYED + COUNTER) THEN
        EXIT DO
    ELSE
        COUNTER = COUNTER + 1
    END IF
LOOP

'打印结论2
PRINT "TO DECLINE 1% WINNING RATE, YOU NEED TO LOSE"; COUNTER; " GAME(S) CONTINUOUSLY"

MISSION2_COMPLETE:

PRG_FINISH:
SLEEP
END

运行结果截图：

END