最短前缀

2.c

#include<stdio.h>
#include<stdlib.h>
int main() {
    int num = 0;
    int i, j, k;
    char a[1001][22] = {0};
    int idx[1001], tmpidx;
    char tmp[22] = {0};

    while (scanf("%s", a[num++]) != EOF);
    for (i = 0; i < num; i++)
        idx[i] = i;

    for (i = 0; i < num; i++)
        for (j = i+1; j < num; j++)
            if (strcmp(a[i], a[j]) > 0) {
                memcpy(tmp, a[i], sizeof(tmp));
                memcpy(a[i], a[j], sizeof(tmp));
                memcpy(a[j], tmp, sizeof(tmp));
                tmpidx = idx[i];
                idx[i] = idx[j];
                idx[j] = tmpidx;
            }

    for (k = 0; k < num; k++) {
        int l, maxj;
        for (i = 0; i < num; i++)
            if (idx[i] == k)
                break;
        l = strlen(a[i]);
        if (i > 0) {
            for (j = 0; j < l && a[i][j] == a[i-1][j]; j++);
            maxj = j;
        }
        if (i < num-1) {
            for (j = 0; j < l && a[i][j] == a[i+1][j]; j++);
            maxj = (j > maxj ? j : maxj);
        }
        strcpy(tmp, a[i]);
        tmp[maxj+1] = '\0';
        printf("%s %s\n", a[i], tmp);
    }
    return 0;
}