哈夫曼编码问题，求解

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct _LETTER
{
    int weight;
    int index;
    char str[28];
} LETTER;
int compare(const void *a, const void *b)
{
    LETTER *p1, *p2;
    p1 = (LETTER *)a;
    p2 = (LETTER *)b;
    return p2->weight - p1->weight;
}
void main()
{
    LETTER let[52];
    int i, offset;
    for (i=0; i<26; i++)
    {
        scanf("%s%d", let[i].str, &let[i].weight);
        let[i].index = 0;
    }
    qsort(let, 26, sizeof(LETTER), compare);
    for (i=25; i>0; i--)
    {
        memcpy(&let[i*2+1], &let[i], sizeof(LETTER));
        memcpy(&let[i*2], &let[i-1], sizeof(LETTER));
        strcat(let[i-1].str, let[i*2+1].str);
        let[i-1].weight += let[i*2+1].weight;
        let[i-1].index = i*2;
        memset(&let[i], 0, sizeof(LETTER));
        qsort(let, i, sizeof(LETTER), compare);
    }
    char code[] = "10110001011100101001111101111110010100111101100101001100111111000";
    offset = 2;
    for (i=0; i<strlen(code); i++)
    {
        offset += '1' - code[i];
        if (strlen(let[offset].str) == 1)
        {
            printf("%c", let[offset].str[0]);
            offset = 2;
        }
        else
        {
            offset = let[offset].index;
        }
    }
    printf("\n");
    if (offset != 2)
    {
        printf("error\n");
    }
}