UVa185 - Roman Numerals

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

#define BUF_LEN 40

void split_input(char *buf, char *a, char *b, char *c);
int is_correct(char *a, char *b, char *c);
int cal_value(char *a);
int map(char c);
int cal_char_num(char *a, char *b, char *c);
void dfs(int cur, char *str);

int dep;
char combuf[BUF_LEN];
int vis[10];
char temp[10];
int combuflen;
int lena, lenb, lenc;
char abuf[BUF_LEN], bbuf[BUF_LEN], cbuf[BUF_LEN];
int solnum;

int main()
{
char buf[BUF_LEN];

#ifndef ONLINE_JUDGE
freopen("d:\\UVa\\uva_in.txt", "r", stdin);
#endif

setvbuf(stdout, NULL, _IONBF, 0);

while (fgets(buf, BUF_LEN, stdin) && buf[0] != '#')
{

split_input(buf, abuf, bbuf, cbuf);
if (is_correct(abuf, bbuf, cbuf))
printf("Correct ");
else
printf("Incorrect ");

dep = cal_char_num(abuf, bbuf, cbuf);
lena = strlen(abuf);
lenb = strlen(bbuf);
lenc = strlen(cbuf);
combuflen = lena + lenb + lenc;

memset(vis, 0, sizeof(vis));
solnum = 0;
strcpy(combuf, abuf);
strcat(combuf, bbuf);
strcat(combuf, cbuf);
dfs(0, combuf);

if (solnum == 0)
printf("impossible\n");
else if (solnum == 1)
printf("valid\n");
else
printf("ambiguous\n");
}

return 0;
}

void split_input(char *buf, char *a, char *b, char *c)
{
int aflag, bflag, cflag;
int alen, blen, clen;
int len;
int i;

len = strlen(buf);

aflag = 1, bflag = 0, cflag = 0;
alen = blen = clen = 0;

for (i = 0; i < len; i++)
{
if (isalpha(buf[i]))
{
if (aflag)
a[alen++] = buf[i];
else if (bflag)
b[blen++] = buf[i];
else if (cflag)
c[clen++] = buf[i];

}
else if (buf[i] == '+')
{
a[alen] = '\0';
aflag = 0;
bflag = 1;
cflag = 0;
}
else if (buf[i] == '=')
{
b[blen] = '\0';
aflag = 0;
bflag = 0;
cflag = 1;
}
}
c[clen] = '\0';
}

int is_correct(char *a, char *b, char *c)
{
int v1, v2, v3;

v1 = cal_value(a);
v2 = cal_value(b);
v3 = cal_value(c);

return v1 + v2 == v3;
}

int cal_value(char *a)
{
int len, i;
int value;
int v1, v2;

len = strlen(a);
value = 0;
for (i = 0; i < len - 1; i++)
{
v1 = map(a[i]);
v2 = map(a[i + 1]);
if (v1 < v2)
value -= v1;
else
value += v1;
}
value += map(a[len - 1]);

return value;

}

int map(char c)
{
int value;

switch (c)
{
case 'I':
value = 1;
break;
case 'V':
value = 5;
break;
case 'X':
value = 10;
break;
case 'L':
value = 50;
break;
case 'C':
value = 100;
break;
case 'D':
value = 500;
break;
case 'M':
value = 1000;
break;
}

return value;
}

int cal_char_num(char *a, char *b, char *c)
{
int alen, blen, clen;
int len = 0;
int i, j;
char ch;

alen = strlen(a);
for (i = 0; i < alen; i++)
{
ch = a[i];
for (j = 0; j < len; j++)
{
if (temp[j] == ch)
break;
}
if (j == len)
temp[len++] = ch;
}

blen = strlen(b);
for (i = 0; i < blen; i++)
{
ch = b[i];
for (j = 0; j < len; j++)
{
if (ch == temp[j])
break;
}
if (j == len)
temp[len++]  = ch;
}

clen = strlen(c);
for (i = 0; i < clen; i++)
{
ch = c[i];
for (j = 0; j < len; j++)
{
if (ch == temp[j])
break;
}
if (j == len)
temp[len++] = ch;
}

temp[len] = '\0';

return len;
}

void dfs(int cur, char *str)
{
int i, j;
int a, b, c;
char tempa[BUF_LEN], tempb[BUF_LEN], tempc[BUF_LEN], s[BUF_LEN];

if (cur >= dep)
{

memcpy(tempa, str, lena);
memcpy(tempb, str + lena, lenb);
memcpy(tempc, str + lena + lenb, lenc);
tempa[lena] = '\0';
tempb[lenb] = '\0';
tempc[lenc] = '\0';

sscanf(tempa, "%d", &a);
sscanf(tempb, "%d", &b);
sscanf(tempc, "%d", &c);
if (a + b == c)
solnum++;
return ;
}

for (i = 0; i < 10; i++)
{

if (!vis[i])
{
strcpy(s, str);
for (j = 0; j < combuflen; j++)
{
if (s[j] == temp[cur])
s[j] = i + '0';
}

if ((lena > 1 && s[0] == '0') || (lenb > 1 && s[lena] == '0') || (lenc > 1 && s[lena + lenb] == '0')) continue;
vis[i] = 1;
dfs(cur + 1, s);
vis[i] = 0;
}

}
}