morse.c

// http://poj.org/problem?id=1051
#include <stdio.h>
#include <string.h>

char hash[32][6]={{".-"},{"-..."},{"-.-."},{"-.."},{"."},{"..-."},{"--."},
            {"...."},{".."},{".---"},{"-.-"},{".-.."},{"--"},{"-."},
            {"---"},{".--."},{"--.-"},{".-."},{"..."},{"-"},{"..-"},
            {"...-"},{".--"},{"-..-"},{"-.--"},{"--.."},{"..--"},{".-.-"},
            {"---."},{"----"}};
int len[32]={2,4,4,3,1,4,3,4,2,4,3,4,2,2,3,4,4,3,3,1,3,4,3,4,4,4,4,4,4,4};

int main()
{
    char str[512];
    int i,j,k,n,num[128];
    scanf("%d",&n); getchar();
    for (i=0; i<n; i++) {
        char ch,buf[6],*p=str;
        int count=0;
        memset(str,0,512);
        while ((ch=getchar())!='\n') {
            num[count] = 4;
            if (ch>='A' && ch <='Z') {
                strcat(str,hash[ch-'A']);
                num[count] = len[ch-'A'];
            }
            else if (ch=='_') strcat(str,hash[26]);
            else if (ch==',') strcat(str,hash[27]);
            else if (ch=='.') strcat(str,hash[28]);
            else if (ch=='?') strcat(str,hash[29]);
            count++;
        }
        printf ( "%d: ",i+1 );
        for (j=count-1; j>=0; j--) {
            strncpy(buf,p,num[j]);
            buf[num[j]] = '\0';
            for (k=0; k<30; k++)
                if (!strcmp(buf,hash[k])) {
                    if (k<26) putchar(k+'A');
                    else if (k==26) putchar('_');
                    else if (k==27) putchar(',');
                    else if (k==28) putchar('.');
                    else if (k==29) putchar('?');
                    break;
                }
            p += num[j];
        }
        printf ( "\n" );
    }
}