js实现字符全排列算法

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>字符全排列</title>
</head>
<body>
     
 
<script>
function charsMap(o){
    o = (o+"").replace(/(\w)(?=\w*\1)/g,"").replace(/\s+/g,""); //去除重复字符以及空白字符
    switch(o.length){
        case 0: 
        case 1: return [o];
        default: 
            var p = /^(\S+?)(\S)$/.exec(o), //使用正则将字符串分割为n-1长度字符串，以及最后一个字符串。
                _r = charsMap(p[1]), 
                l = p[2], 
                r = [];
             
            for (var i = 0; i < _r.length; i++) {
                var t = _r[i];
                for (var j = 0, len = t.length; j <= len; j++) {
                    r.push( t.replace( new RegExp("^(\\S{"+j+"})(\\S{"+(len-j)+"})$"), "$1"+l+"$2" ) ); 
                    //字符插入位置从开头前到结尾后,正则的作用相当于Array.splice(j,0,l); 在下标j的位置插入一个字符l
                }
            }
            return r;
    }
}
 
var arr = "abcde";
var t = new Date().getTime();
var result = charsMap(arr);
document.write( "总耗时："+(new Date().getTime()-t)+"ms" );
 
    var html = "<ul><li>" + result.join("</li><li>") + "</li></ul>";
    document.write(html);
</script>
</body>
</html>
更多相关文章

随机推荐
