求个算法. 应该个是排列问题
今天看到有人问,觉得有点意思,来这里看下大家有什么好点的算法.
题:单词"character",要求里面有4个字母是大写的，其它小写.列出所有的组合.
请教...
[解决办法]
var a=[];function comb(m,k){ var i,j; for(i=m;i>=k;i--){ a[k]=i; if(k>1) comb(i-1,k-1); else{ for (j=a[0];j>0;j--) document.write(a[j]); document.write("\n"); } }} function main(){ a[0]=4; comb(9,4); }main();
[解决办法]
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <meta http-equiv="Create-Date" content="Feb 28, 2008" /> <title>Test</title> <script type="text/javascript">var gen = function (arr, length, n) {// document.write ('length=' + length + '; n=' + n + '; ');// show (arr);// alert ('go'); if (length == n) { for (var i=0; i<length; i++) { arr[i] = arr[i].toUpperCase(); } show(arr); return ; } if (length > n) { arr[length-1] = arr[length-1].toLowerCase(); gen(arr, length-1, n); } if (n > 0) { arr[length-1] = arr[length-1].toUpperCase(); gen(arr, length-1, n-1); }}function show(arr) { for (var i=0; i<arr.length; i++) { document.write(arr[i]); } document.write("<br />");}function str2arr (str) { var arr = []; for (var i=0; i<str.length; i++) { arr.push(str[i]); } return arr;}function main() { var arr = str2arr('character'); gen (arr, arr.length, 4); document.close();} </script> </head> <body> <a href="javascript:main()">Exec</a> </body></html>