The Island of Logic has three kinds of inhabitants: divine beings that always tell the truth, evil
beings that always lie, and human beings that are truthful during the day and lie at night. Every
inhabitant recognizes the type of every other inhabitant.
A social scientist wants to visit the island. Because he is not able to distinguish the three kinds
of beings only from their looks, he asks you to provide a communication analyzer that deduces facts
from conversations among inhabitants. The interesting facts are whether it is day or night and what
kind of beings the speakers are.
The input file contains several descriptions of conversations. Each description starts with an integer
n, the number of statements in the conversation. The following n lines each contain one statement by
an inhabitant. Every statement line begins with the speaker's name, one of the capital letters A, B, C,
D, E, followed by a colon `:'. Next is one of the following kinds of statements:
I am [not] ( divine | human | evil | lying ).
- X
is [not] ( divine | human | evil | lying ).
It is ( day | night ).
Square brackets [] mean that the word in the brackets may or may not appear, round brackets ()
mean that exactly one of the alternatives separated by | must appear. X stands for some name from A, B, C,
D, E. There will be no two consecutive spaces in any statement line, and at most 50 statements
in a conversation.
The input is terminated by a test case starting with n = 0.
For each conversation, first output the number of the conversation in the format shown in the sample
output. Then print ``This is impossible.'', if the conversation cannot happen according to the
rules or ``No facts are deducible.'', if no facts can be deduced. Otherwise print all the facts
that can be deduced. Deduced facts should be printed using the following formats:
- X
is ( divine | human | evil ).
It is ( day | night ).
X is to be replaced by a capital letter speaker name. Facts about inhabitants must be given first (in
alphabetical order), then it may be stated whether it is day or night.
The output for each conversation must be followed by a single blank line.
1
A: I am divine.
1
A: I am lying.
1
A: I am evil.
3
A: B is human.
B: A is evil.
A: B is evil.
0
Conversation #1
No facts are deducible.
Conversation #2
This is impossible.
Conversation #3
A is human.
It is night.
Conversation #4
A is evil.
B is divine.
To make things clearer, we will show the reasoning behind the third input example, where A says
``I am evil.''. What can be deduced from this? Obviously A
cannot be divine, since she would be lying, similarly A cannot be evil,
since she would tell the truth. Therefore, A must be human, moreover,
since she is lying, it must be night. So the correct output is as shown.
In the fourth input example, it is obvious that A is lying since her two statements are contradictory.
So, B can be neither human nor evil, and consequently must be divine. B always tells the truth, thus
A must be evil. Voil‘a!
Miguel A. Revilla
1998-03-10
枚舉 A, B, C, D, E 的種族(神族、蟲族、人族) 以及當時是 day/night
因此枚舉量 3^5 * 2 = 486
之後檢察矛盾狀況。檢查比較麻煩，只要有一個變數寫錯就掛了，因此 WA 很多次。
如果會寫 check model 的話，檢查應該比較好寫，但我仍不會。
當得到一種可行解時，在 Table 上標記。
最後檢查 A, B, C, D, E 是不是只能當某單一個種族，如果是的話直接印出。
同理 day/night
如果 Table 上沒有任何標記，就是無解的情況。
如果沒有任何可以推論的情況，就輸出 No facts are deducible.
#include <stdio.h>
#include <string.h>
char stmt[105][105];
int n, kind[10], table[10][3];
void check() {
int i;
char f1[20], f2[20], f3[20], f4[20], who[20];
//printf("%d %d %d %d %d %d ---\n", kind[0], kind[1], kind[2], kind[3], kind[4], kind[5]);
for(i = 0; i < n; i++) {
if(sscanf(stmt[i], "%s %s %s %s %s", who, f1, f2, f3, f4) == 5) {
// I/X am/is not (divine, human, evil, lying);
if(f1[0] == 'I' && f1[1] == '\0') {
if(kind[who[0]-'A'] == 0) {// divine
if(f4[0] == 'd') {return;} // I am not divine.
}
if(kind[who[0]-'A'] == 1) {// evil
if(f4[0] == 'e' || f4[0] == 'l') {} // I am not evil, I am not lying.
else
return;
}
if(kind[who[0]-'A'] == 2) {// human
if(kind[5] == 0) {// day
if(f4[0] == 'h') {return;} // I am not human
} else {// night
if(f4[0] == 'h' || f4[0] == 'l') {}// I am not human, I am not lying.
else
return;
}
}
} else {
if(kind[who[0]-'A'] == 0 || (kind[who[0]-'A'] == 2 && kind[5] == 0)) {
// [truth fact] X is not
if(kind[f1[0]-'A'] == 0 && f4[0] == 'd') // X is not divine
return;
if(kind[f1[0]-'A'] == 1 && f4[0] == 'e') // X is not evil
return;
if(kind[f1[0]-'A'] == 2 && f4[0] == 'h') // X is not human
return;
if(f4[0] == 'l') { // X is not lying. X must be divine, or human in day.
if(kind[f1[0]-'A'] == 0 || (kind[f1[0]-'A'] == 2 && kind[5] == 0)) {}
else
return;
}
} else { //[not truth fact]
if(kind[f1[0]-'A'] == 0 && (f4[0] == 'e' || f4[0] == 'h')) // X is not evil. => true stmt => but who say not truth.
return;
if(kind[f1[0]-'A'] == 1 && (f4[0] == 'd' || f4[0] == 'h'))
return;
if(kind[f1[0]-'A'] == 2 && (f4[0] == 'd' || f4[0] == 'e'))
return;
if(f4[0] == 'l') {// !(X is not lying.) X must be evil, or human in night.
if(kind[f1[0]-'A'] == 1 || (kind[f1[0]-'A'] == 2 && kind[5] == 1)) {}
else
return;
}
}
}
} else {
sscanf(stmt[i], "%s %s %s %s", who, f1, f2, f3);
//printf("%s %s %s %d\n", f3, f2, f1, kind[0]);
// I/X am/is (divine, human, evil, lying)
// It is (day, night)
if(f1[0] == 'I' && f1[1] == 't') {
if(kind[who[0]-'A'] == 0 || (kind[who[0]-'A'] == 2 && kind[5] == 0)) {
if(kind[5] == 0 && f3[0] == 'n')
return;
if(kind[5] == 1 && f3[0] == 'd')
return;
} else {
if(kind[5] == 0 && f3[0] == 'd')
return;
if(kind[5] == 1 && f3[0] == 'n')
return;
}
} else if(f1[0] == 'I' && f1[1] == '\0') {
if(kind[who[0]-'A'] == 0) {// divine
if(f3[0] != 'd') {return;} // I am (evil/human/lying).
}
if(kind[who[0]-'A'] == 1) {// evil
if(f3[0] == 'l' || f3[0] == 'e') {return;} // I am lying. I am evil.
}
if(kind[who[0]-'A'] == 2) {// human
if(kind[5] == 0) {// day
if(f3[0] != 'h') {return;} // I am (lying/evil/divine).
} else {// night
if(f3[0] == 'h' || f3[0] == 'l') {return;} // I am human.
}
}
} else {
if(kind[who[0]-'A'] == 0 || (kind[who[0]-'A'] == 2 && kind[5] == 0)) {
// [truth fact]
if(kind[f1[0]-'A'] != 0 && f3[0] == 'd') // X is divine.
return;
if(kind[f1[0]-'A'] != 1 && f3[0] == 'e')
return;
if(kind[f1[0]-'A'] != 2 && f3[0] == 'h')
return;
if(f3[0] == 'l') { // X is lying. X must be evil, or human in night.
if(kind[f1[0]-'A'] == 1 || (kind[f1[0]-'A'] == 2 && kind[5] == 1)) {}
else
return;
}
} else { //[not truth fact]
if(kind[f1[0]-'A'] == 0 && f3[0] == 'd') // X is divine.
return;
if(kind[f1[0]-'A'] == 1 && f3[0] == 'e')
return;
if(kind[f1[0]-'A'] == 2 && f3[0] == 'h')
return;
if(f3[0] == 'l') {// !(X is lying.) X must be divine, or human in day.
if(kind[f1[0]-'A'] == 0 || (kind[f1[0]-'A'] == 2 && kind[5] == 0)) {}
else
return;
}
}
}
}
}
// printf("%d %d %d %d %d %d***\n", kind[0], kind[1], kind[2], kind[3], kind[4], kind[5]);
for(i = 0; i < 6; i++)
table[i][kind[i]] = 1;
/*for(i = 0; i < 5; i++) {
printf("%c %s\n", i+'A', kind[i] == 0 ? "divine" : (kind[i]==1?"evil":"human"));
}
if(kind[5] == 0)
puts("day");
else
puts("night");
puts("++++");*/
}
void dfs(int nd) {
if(nd == 6) {
check();
return ;
}
kind[nd] = 0; // divine/day
dfs(nd+1);
kind[nd] = 1; // evil/night
dfs(nd+1);
if(nd != 5) {
kind[nd] = 2;// human
dfs(nd+1);
}
}
int main() {
/*freopen("in.txt", "r+t", stdin);
freopen("out2.txt", "w+t", stdout);*/
int i, cases = 0;
while(scanf("%d", &n) == 1 && n) {
while(getchar() != '\n');
for(i = 0; i < n; i++)
gets(stmt[i]);
memset(table, 0, sizeof(table));
dfs(0);
printf("Conversation #%d\n", ++cases);
int hasSol = 1, fact = 0, cnt;
for(i = 0; i < 6; i++) {
if(i != 5)
cnt = table[i][0]+table[i][1]+table[i][2];
else
cnt = table[i][0]+table[i][1];
if(cnt == 0) hasSol = 0;
if(cnt == 1) fact = 1;
}
if(!hasSol) {
puts("This is impossible.\n");
continue;
}
if(fact == 0) {
puts("No facts are deducible.\n");
continue;
}
for(i = 0; i < 6; i++) {
if(i != 5)
cnt = table[i][0]+table[i][1]+table[i][2];
else
cnt = table[i][0]+table[i][1];
if(cnt == 1) {
if(i < 5) {
printf("%c is ", i+'A');
if(table[i][0])
puts("divine.");
else if(table[i][1])
puts("evil.");
else
puts("human.");
} else {
if(table[i][0])
puts("It is day.");
else
puts("It is night.");
}
}
}
puts("");
}
return 0;
}
/*
10
C: D is human.
D: C is not evil.
D: E is not human.
D: E is not lying.
A: I am not human.
C: D is not divine.
D: I am not human.
A: E is not evil.
A: B is human.
C: A is not divine.
*/
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