UVA 644 Immediate Decodability

        排序后相似前缀就会相邻，那样就比较好处理了。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define min(a, b) ((a)<(b)?(a):(b))

char str[1000][100];

int cmp(const void* _a, const void *_b) {
    char *a = (char*)_a;
    char *b = (char*)_b;

    return strcmp(a, b);
}

bool is_decode(int n) {
    int i, j, m;
    for (i=1; i<n; i++) {
        m = min(strlen(str[i-1]), strlen(str[i]));
        for (j=0; j<m; j++)
            if (str[i][j] != str[i-1][j])
                break;
        if (j == m) return false;
    }

    return true;
}

int main() {


    int count = 1;
    while (scanf("%s", str[0]) != EOF) {
        int i = 1;
        while (scanf("%s", str[i]) && str[i][0] != '9')
            i++;

        qsort(str, i, sizeof (str[0]), cmp);

        if (is_decode(i))
            printf("Set %d is immediately decodable\n", count++);
        else
            printf("Set %d is not immediately decodable\n", count++);

    }

    return 0;
}