Bash-如何使Bash更高效、运行更快_Bash_Performance_Variables_If Statement_Do While

Bash-如何使Bash更高效、运行更快

bash performance variables if-statement

Bash-如何使Bash更高效、运行更快,bash,performance,variables,if-statement,do-while,Bash,Performance,Variables,If Statement,Do While,有没有办法让代码运行得更快？我什么都试过了基本上我想做的是：计算52个变量的所有组合，但仅显示所有数字只列出一次的组合！所以不可能有外汇：两个1或三个49 #!/bin/bash #Enter here how many cards you use howmanycards=52; let run=$howmanycards+1; i=1; u=52; totalrun=0; SECONDS=0; while [ $i -lt $run ]; do let card$i=$u;

有没有办法让代码运行得更快？我什么都试过了

基本上我想做的是：计算52个变量的所有组合，但仅显示所有数字只列出一次的组合！所以不可能有外汇：两个1或三个49

#!/bin/bash

#Enter here how many cards you use
howmanycards=52;

let run=$howmanycards+1;
i=1;
u=52;
totalrun=0;
SECONDS=0;

while [ $i -lt $run ]; do
    let card$i=$u;
    let i++;
    let u--;
done

while [ -lt ]; do

    let i=1;

    if [ "$card1" -gt "52" ]; then let card2++;let card1=1; fi
    if [ "$card2" -gt "52" ]; then let card3++;let card2=1; fi
    if [ "$card3" -gt "52" ]; then let card4++;let card3=1; fi
    if [ "$card4" -gt "52" ]; then let card5++;let card4=1; fi
    if [ "$card5" -gt "52" ]; then let card6++;let card5=1; fi
    if [ "$card6" -gt "52" ]; then let card7++;let card6=1; fi
    if [ "$card7" -gt "52" ]; then let card8++;let card7=1; fi
    if [ "$card8" -gt "52" ]; then let card9++;let card8=1; fi
    if [ "$card9" -gt "52" ]; then let card10++;let card9=1; fi
    if [ "$card10" -gt "52" ]; then let card11++;let card10=1; fi
    if [ "$card11" -gt "52" ]; then let card12++;let card11=1; fi
    if [ "$card12" -gt "52" ]; then let card13++;let card12=1; fi
    if [ "$card13" -gt "52" ]; then let card14++;let card13=1; fi
    if [ "$card14" -gt "52" ]; then let card15++;let card14=1; fi
    if [ "$card15" -gt "52" ]; then let card16++;let card15=1; fi
    if [ "$card16" -gt "52" ]; then let card17++;let card16=1; fi
    if [ "$card17" -gt "52" ]; then let card18++;let card17=1; fi
    if [ "$card18" -gt "52" ]; then let card19++;let card18=1; fi
    if [ "$card19" -gt "52" ]; then let card20++;let card19=1; fi
    if [ "$card20" -gt "52" ]; then let card21++;let card20=1; fi
    if [ "$card21" -gt "52" ]; then let card22++;let card21=1; fi
    if [ "$card22" -gt "52" ]; then let card23++;let card22=1; fi
    if [ "$card23" -gt "52" ]; then let card24++;let card23=1; fi
    if [ "$card24" -gt "52" ]; then let card25++;let card24=1; fi
    if [ "$card25" -gt "52" ]; then let card26++;let card25=1; fi
    if [ "$card26" -gt "52" ]; then let card27++;let card26=1; fi
    if [ "$card27" -gt "52" ]; then let card28++;let card27=1; fi
    if [ "$card28" -gt "52" ]; then let card29++;let card28=1; fi
    if [ "$card30" -gt "52" ]; then let card31++;let card30=1; fi
    if [ "$card31" -gt "52" ]; then let card32++;let card31=1; fi
    if [ "$card32" -gt "52" ]; then let card33++;let card32=1; fi
    if [ "$card33" -gt "52" ]; then let card34++;let card33=1; fi
    if [ "$card34" -gt "52" ]; then let card35++;let card34=1; fi
    if [ "$card35" -gt "52" ]; then let card36++;let card35=1; fi
    if [ "$card36" -gt "52" ]; then let card37++;let card36=1; fi
    if [ "$card37" -gt "52" ]; then let card38++;let card37=1; fi
    if [ "$card38" -gt "52" ]; then let card39++;let card38=1; fi
    if [ "$card39" -gt "52" ]; then let card40++;let card39=1; fi
    if [ "$card40" -gt "52" ]; then let card41++;let card40=1; fi
    if [ "$card41" -gt "52" ]; then let card42++;let card41=1; fi
    if [ "$card42" -gt "52" ]; then let card43++;let card42=1; fi
    if [ "$card43" -gt "52" ]; then let card44++;let card43=1; fi
    if [ "$card44" -gt "52" ]; then let card45++;let card44=1; fi
    if [ "$card45" -gt "52" ]; then let card46++;let card45=1; fi
    if [ "$card46" -gt "52" ]; then let card47++;let card46=1; fi
    if [ "$card47" -gt "52" ]; then let card48++;let card47=1; fi
    if [ "$card48" -gt "52" ]; then let card49++;let card48=1; fi
    if [ "$card49" -gt "52" ]; then let card50++;let card49=1; fi
    if [ "$card50" -gt "52" ]; then let card51++;let card50=1; fi
    if [ "$card51" -gt "52" ]; then let card52++;let card51=1; fi

    while [ $i -lt $run ]; do
        temp=${card}${i};
        if [ "$temp" = "$card1" ] || [ "$temp" = "$card2" ] || 
           [ "$temp" = "$card3" ] || [ "$temp" = "$card4" ] || 
           [ "$temp" = "$card5" ] || [ "$temp" = "$card6" ] || 
           [ "$temp" = "$card7" ] || [ "$temp" = "$card8" ] || 
           [ "$temp" = "$card9" ] || [ "$temp" = "$card10" ] || 
           [ "$temp" = "$card11" ] || [ "$temp" = "$card12" ] || 
           [ "$temp" = "$card13" ] || [ "$temp" = "$card14" ] || 
           [ "$temp" = "$card15" ] || [ "$temp" = "$card16" ] || 
           [ "$temp" = "$card17" ] || [ "$temp" = "$card18" ] || 
           [ "$temp" = "$card19" ] || [ "$temp" = "$card20" ] || 
           [ "$temp" = "$card21" ] || [ "$temp" = "$card22" ] || 
           [ "$temp" = "$card23" ] || [ "$temp" = "$card24" ] || 
           [ "$temp" = "$card25" ] || [ "$temp" = "$card26" ] || 
           [ "$temp" = "$card27" ] || [ "$temp" = "$card28" ] || 
           [ "$temp" = "$card29" ] || [ "$temp" = "$card30" ] || 
           [ "$temp" = "$card31" ] || [ "$temp" = "$card32" ] || 
           [ "$temp" = "$card33" ] || [ "$temp" = "$card34" ] || 
           [ "$temp" = "$card35" ] || [ "$temp" = "$card36" ] || 
           [ "$temp" = "$card37" ] || [ "$temp" = "$card38" ] || 
           [ "$temp" = "$card39" ] || [ "$temp" = "$card40" ] || 
           [ "$temp" = "$card41" ] || [ "$temp" = "$card42" ] || 
           [ "$temp" = "$card43" ] || [ "$temp" = "$card44" ] || 
           [ "$temp" = "$card45" ] || [ "$temp" = "$card46" ] || 
           [ "$temp" = "$card47" ] || [ "$temp" = "$card48" ] || 
           [ "$temp" = "$card49" ] || [ "$temp" = "$card50" ] || 
           [ "$temp" = "$card51" ] || [ "$temp" = "$card52" ]; then
            let usefull++;
        fi
        let i++;
    done

if [ $usefull -gt 51 ]; then
    echo "[loops($totalrun)]    $card52-$card51-$card50-$card49-$card48-$card47-$card46-$card45-$card44-$card43-$card42-$card41-$card40-$card39-$card38-$card37-$card36-$card35-$card34-$card33-$card32-$card31-$card30-$card29-$card28-$card27-$card26-$card25-$card24-$card23-$card22-$card21-$card20-$card19-$card18-$card17-$card16-$card15-$card14-$card13-$card12-$card11-$card10-$card9-$card8-$card7-$card6-$card5-$card4-$card3-$card2-$card1";
fi

let usefull=0;

if [ "$card52" -gt "52" ]; then
    echo " ";
    duration=$SECONDS
    echo "$(($duration / 60)) min and $(($duration % 60)) sec";
    exit;
fi

let card1++;
let totalrun++;
done

我尝试过创建代码优先级，但似乎没有什么不同

但我发现，如果代码中有多个数字，那么进行检查的代码将使用大量性能！我不知道该怎么办

谢谢您的帮助。

首先，我认为您需要一个可行的实现来获得bash中的组合。下面是一个适用于关联数组的。我实现它是为了模仿：

现在，我们可以开始考虑修改

combine（）

函数，以附加一个条件，即我们只打印集合（只包含不同元素的数组），这样我们就可以替换该行：

echo ${postfix[@]}

通过新呼叫：

echo_if_is_a_set postfix[@]

其实施方式如下：

function echo_if_is_a_set() {
    local -a input=("${!1}")
    local -a entry_count_lookup

    # Tally up the occurrences of each item.
    for item in ${input[@]}; do
        local current_count=${entry_count_lookup[$item]:-0}
        ((current_count++))
        entry_count_lookup[$item]=$current_count
    done

    for value in ${!entry_count_lookup[@]}; do
        if [ ${entry_count_lookup[$value]} -ne 1 ]; then
            return
        fi
    done

    echo ${input[@]}
}

好的，但还没做完。如果在repeat元素中传递相同的组合，我们可能仍然会打印两次。例如，如果您这样做了：

foo=(1 1 1)
get_combinations foo[@]

那么，让我们调用uniq，将

get\u组合

更改为：

function get_combinations() {
    local -a prefix_table=("${!1}")
    local -a postfix_table=()
    local index=0

    combine 0 prefix_table[@] postfix_table[@] | sort | uniq
}

而且，我们完成了。使用输入

（{1..3}）

运行此命令将打印：

但是这个实现的好处在于，因为它使用了关联数组，所以我们实际上可以是通用的，并输入类似于

（2 Racecar 34）

，它将返回：

2
2 34
2 Racecar
2 Racecar 34
34
Racecar
Racecar 34

无论如何，作为最后的评论，我想说的是，从这样的事情开始，然后你可以优化算法以提高效率

此外，Bash可能根本就不适合这种语言-首先，我认为您需要一个可行的实现来获得bash中的组合。下面是一个适用于关联数组的。我实现它是为了模仿：