UVA - 565 Pizza Anyone?（状态压缩+暴利枚举）
| Pizza Anyone? |
You are responsible for ordering a large pizza for you and your friends. Each of them has told you what he wants on a pizza and what he does not; of course they all understand that since there is only going to be one pizza, no one is likely to have all their requirements satisfied. Can you order a pizza that will satisfy at least one request from all your friends?
The pizza parlor you are calling offers the following pizza toppings; you can include or omit any of them in a pizza:
| Input Code | Topping |
| A | Anchovies |
| B | Black Olives |
| C | Canadian Bacon |
| D | Diced Garlic |
| E | Extra Cheese |
| F | Fresh Broccoli |
| G | Green Peppers |
| H | Ham |
| I | Italian Sausage |
| J | Jalapeno Peppers |
| K | Kielbasa |
| L | Lean Ground Beef |
| M | Mushrooms |
| N | Nonfat Feta Cheese |
| O | Onions |
| P | Pepperoni |
Your friends provide you with a line of text that describes their pizza preferences. For example, the line
+O-H+P;
reveals that someone will accept a pizza with onion, or without ham, or with pepperoni, and the line
-E-I-D+A+J;
indicates that someone else will accept a pizza that omits extra cheese, or Italian sausage, or diced garlic, or that includes anchovies or jalapenos.
Input
The input consists of a series of pizza constraints.A pizza constraint is a list of 1 to 12 topping constraint lists each on a line by itself followed by a period on a line by itself.
A topping constraint list is a series of topping requests terminated by a single semicolon.
An topping request is a sign character (+/-) and then an uppercase letter from A to P.
Output
For each pizza constraint, provide a description of a pizza that satisfies it. A description is the string `` Toppings: " in columns 1 through 10 and then a series of letters, in alphabetical order, listing the toppings on the pizza. So, a pizza with onion, anchovies, fresh broccoli and Canadian bacon would be described by:
Toppings: ACFO
If no combination toppings can be found which satisfies at least one request of every person, your program should print the string
No pizza can satisfy these requests.
on a line by itself starting in column 1.
Sample Input
+A+B+C+D-E-F-G-H; -A-B+C+D-E-F+G+H; -A+B-C+D-E+F-G+H; . +A+B+C+D; +E+F+F+H; +A+B-G; +O+J-F; +H+I+C; +P; +O+M+L; +M-L+P; . +A+B+C+D; +E+F+F+H; +A+B-G; +P-O; +O+J-F; +H+I+C; +P; +O; +O+M+L; -O-P; +M-L+P; .
Sample Output
Toppings: Toppings: CELP No pizza can satisfy these requests.
题目大意：
你负责去订购一个大比萨， 你的朋友们对于要添加什么或者不添加什么都有不同的要求。但是你的朋友们也知道不可能满足全部的要求。所以你要选择一个订购方案，让所有人至少满足其中一个要求。 注意，如果某人不想要哪个，那么不添加那个也算是满足了他的一个要求。
分析与总结：
题目只有16种东西选择， 对于每种东西之是选择或者不选泽两种状态。那么用暴力枚举法完全可以做出。
用一个数字，它的各个二进制位表示定或者不定。枚举0 ～ (1<<16)-1即可。
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
const int N = 100;
char str[N][N];
inline bool judge(int status,int cur) {
int len = strlen(str[cur]);
for (int pos = 0; pos < len; pos += 2) {
if(str[cur][pos] == '+') {
if((status >> (str[cur][pos+1]) - 'A') & 1) {
return true;
}
}else if(str[cur][pos] == '-') {
if(~(status >> (str[cur][pos+1] - 'A')) & 1) {
return true;
}
}
}
return false;
}
int main() {
int cnt = 0;
while(scanf("%s",str[cnt]) != EOF) {
if(str[cnt][0] == '.') {
int status;
bool flag;
for (status = 0; status < 1<<16; status++) {
flag = true;
for (int i = 0; i < cnt; i++) {
bool ok = judge(status,i); //判断是否符合要求，如果有一个不符合要求就退出
if (!ok) {
flag = false;
break;
}
}
if(flag) {
break;
}
}
if(!flag) {
printf("No pizza can satisfy these requests.\n");
}else {
printf("Toppings: ");
for(int i = 0; i < 16; i++) {
if(status & 1) {
printf("%c",i+'A');
}
status >>= 1;
}
printf("\n");
}
cnt = -1;
}
cnt++;
}
return 0;
}