題目:POJ1013稱硬幣
題目描述:有12枚硬幣。其中有11枚真幣和1枚假幣。假幣和真幣重量不同,但不知道假幣比真幣輕還是重。現在,用一架天平稱了這些幣三次,告訴你稱的結果,請你找出假幣並且確定假幣是輕是重(數據保證一定能找出來)。
●輸入樣例 注意:天平左右的硬幣數總是相等的,even,up,down指的是天平右側的狀態
2
ABCD EFGH even
ABCI EFJK up
ABIJ EFGH even
ABCD IJKL even
ABCE GJKL even
ABCF AGKL up
●輸出樣例
K is the counterfeit coin and it is light.
F is the counterfeit coin and it is heavy.
題解:
枚舉法,枚舉第i枚硬幣爲輕、重兩種情況,如果符合三次稱量即輸出。
程序(這是郭煒老師的程序)
#include <iostream>
#include <string>
#include <vector>
using namespace std;
#define light false
#define heavy true
vector<string> L;//天平左
vector<string> R;//天平右
vector<string> S;//天平狀態
bool isFalse(char c, bool b)
{
string Left, Right, State;
for (int i = 0; i < 3; i++) {
if (b == light) {
Left = L[i];
Right = R[i];
}
else{
Left = R[i];
Right = L[i];
}
State = S[i];
switch (State[0]) {
case 'u':
if (Left.find(c) != string::npos)
return false;
break;
case 'e':
if (Left.find(c) != string::npos || Right.find(c) != string::npos)
return false;
break;
case 'd':
if (Right.find(c) != string::npos)
return false;
break;
}
}
return true;
}
int main()
{
int N;
cin >> N;
for (int i = 0; i < N; i++) {
string s1, s2, s3;
for (int j = 0; j < 3; j++) {
cin >> s1 >> s2 >> s3;
L.push_back(s1);
R.push_back(s2);
S.push_back(s3);
}
for (char c = 'A'; c <= 'L'; c++) {
if (isFalse(c, light)) {
cout << c << " is the counterfeit coin and it is light." << endl;
break;
}
if (isFalse(c, heavy)) {
cout << c << " is the counterfeit coin and it is heavy." << endl;
break;
}
}
L.clear();
R.clear();
S.clear();
}
system("pause");
return 0;
}