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## why --------- ! [ s[len] = 0; ] -------- WA, --or---AC???????????????????????????

Posted by 20091101579 at 2011-04-11 14:09:49 on Problem 1256
In Reply To:递归，代码，此题坚决不用STL，那样太没意思 Posted by:smilerxz at 2009-08-12 15:59:26
```> #include <iostream>
> #include <algorithm>
> using namespace std;
>
> #define MAXN 13
>
> char a[MAXN + 1];
> int len;
> char flag[MAXN];
> char s[MAXN + 1];
>
> bool cmp(char a, char b) {
>     return tolower(a) == tolower(b) ? a < b : tolower(a) < tolower(b);
> }
>
> void solve(int n) {
>     if (n == len) {
>         puts(s);
>         return;
>     }
>     for (int i = 0; i < len; i++) {
>         if (! flag[i]) {
>             flag[i] = 1;
>             s[n] = a[i];
>             solve(n + 1);
>             flag[i] = 0;
>             while (i + 1 < len && a[i + 1] == a[i]) i++;
>         }
>     }
> }
>
> int main() {
>     int CASE;
>     scanf("%d", &CASE);
>     while (CASE--) {
>         scanf("%s", a);
>         len = strlen(a);
>         sort(a, a + len, cmp);
>         memset(flag, 0, sizeof(flag));
>         s[len] = 0;
>         solve(0);
>     }
>     return 0;
> }
```

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