题解 | 字符串排序

typedef struct {
    int i;
    char c;
} e;

const int N = 1000;
char s[N];
e a[N];

int cmp(const void* a, const void* b) {
    e x = *(e*)a, y = *(e*)b;
    if (x.c > 'Z') x.c -= 32;
    if (y.c > 'Z') y.c -= 32;
    return x.c != y.c ? x.c - y.c : x.i - y.i;
}

int main() {
    while (gets(s)) {
        int n = strlen(s), m = 0;
        for (int i = 0; i < n; i++)
            if (isalpha(s[i])) {
                a[m].i = i;
                a[m].c = s[i];
                m++;
            }
        qsort(a, m, sizeof(e), cmp);
        for (int i = 0, j = 0; i < n; i++)
            if (isalpha(s[i]))
                s[i] = a[j++].c;
        puts(s);
    }
    return 0;
}