北大oj1013——Counterfeit Dollar

Counterfeit Dollar

Time Limit: 1000MS Memory Limit: 10000K

Description

Sally Jones has a dozen Voyageur silver dollars. However, only eleven of the coins are true silver dollars; one coin is counterfeit even though its color and size make it indistinguishable from the real silver dollars. The counterfeit coin has a different weight from the other coins but Sally does not know if it is heavier or lighter than the real coins.
Happily, Sally has a friend who loans her a very accurate balance scale. The friend will permit Sally three weighings to find the counterfeit coin. For instance, if Sally weighs two coins against each other and the scales balance then she knows these two coins are true. Now if Sally weighs
one of the true coins against a third coin and the scales do not balance then Sally knows the third coin is counterfeit and she can tell whether it is light or heavy depending on whether the balance on which it is placed goes up or down, respectively.
By choosing her weighings carefully, Sally is able to ensure that she will find the counterfeit coin with exactly three weighings.

Input

The first line of input is an integer n (n > 0) specifying the number of cases to follow. Each case consists of three lines of input, one for each weighing. Sally has identified each of the coins with the letters A--L. Information on a weighing will be given by two strings of letters and then one of the words up'',down'', or ``even''. The first string of letters will represent the coins on the left balance; the second string, the coins on the right balance. (Sally will always place the same number of coins on the right balance as on the left balance.) The word in the third position will tell whether the right side of the balance goes up, down, or remains even.

Output

For each case, the output will identify the counterfeit coin by its letter and tell whether it is heavy or light. The solution will always be uniquely determined.

Sample Input

1
ABCD EFGH even
ABCI EFJK up
ABIJ EFGH even

Sample Output

K is the counterfeit coin and it is light.

比较简单的一道题，跑了一遍讨论区里给的数据就过了。
让人比较感慨的一件事是，当年大一进acm社区时，学长给的就是这道题，如果有12个硬币，其中有一个是假的，有一个水平秤，不知假币轻重，问我们怎么才能判别哪个是假的。
当时其实想到了给每个硬币编号，然后放上去对比，但是好像用二分法感觉也能往下走，最后时间不够了，最终也没算出来，就没进acm社团，哈哈哈，其实挺后悔的。

#include<iostream>
#include<vector>
using namespace std;

int main()
{
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        vector<int> errorTableUp;
        vector<int> errorTableDown;
        vector<int> rightTable;
        bool isFirstError = true;
        vector<int>::iterator it;

        for (int j = 0; j < 3; j++) {
            int index = 0;
            int curIndex = 0;
            char cin_str[100];
            char cin_Left[13];
            char cin_Right[13];
            char result[10];
            cin >> cin_Left >> cin_Right >> result;

            if (result[0] == 'e') {
                for (int m = 0; cin_Left[m] != NULL; m++) {
                    rightTable.push_back(cin_Left[m]);
                }
                for (int m = 0; cin_Right[m] != NULL; m++) {
                    rightTable.push_back(cin_Right[m]);
                }
            }
            else {
                if (isFirstError) {
                    if (result[0] == 'u') {
                        for (int m = 0; cin_Left[m] != NULL; m++) {
                            errorTableDown.push_back(cin_Left[m]);
                        }
                        for (int m = 0; cin_Right[m] != NULL; m++) {
                            errorTableUp.push_back(cin_Right[m]);
                        }
                    }
                    else if (result[0] == 'd') {
                        for (int m = 0; cin_Left[m] != NULL; m++) {
                            errorTableUp.push_back(cin_Left[m]);
                        }
                        for (int m = 0; cin_Right[m] != NULL; m++) {
                            errorTableDown.push_back(cin_Right[m]);
                        }
                    }

                    isFirstError = false;
                }
                else {
                    vector<int> errorTableDownNew(errorTableDown);
                    errorTableDown.clear();
                    vector<int> errorTableUpNew(errorTableUp);
                    errorTableUp.clear();
                    if (result[0] == 'u') {
                        for (int m = 0; cin_Left[m] != NULL; m++) {
                            for (it = errorTableDownNew.begin(); it != errorTableDownNew.end(); it++) {
                                if (cin_Left[m] == (*it)) {
                                    errorTableDown.push_back((*it));
                                    break;
                                }
                            }
                        }
                        for (int m = 0; cin_Right[m] != NULL; m++) {
                            for (it = errorTableUpNew.begin(); it != errorTableUpNew.end(); it++) {
                                if (cin_Right[m] == (*it)) {
                                    errorTableUp.push_back((*it));
                                    break;
                                }
                            }
                        }
                    }
                    else if (result[0] == 'd') {
                        for (int m = 0; cin_Left[m] != NULL; m++) {
                            for (it = errorTableUpNew.begin(); it != errorTableUpNew.end(); it++) {
                                if (cin_Left[m] == (*it)) {
                                    errorTableUp.push_back((*it));
                                    break;
                                }
                            }
                        }
                        for (int m = 0; cin_Right[m] != NULL; m++) {
                            for (it = errorTableDownNew.begin(); it != errorTableDownNew.end(); it++) {
                                if (cin_Right[m] == (*it)) {
                                    errorTableDown.push_back((*it));
                                    break;
                                }
                            }
                        }
                    }
                }
            }
        }
        char errorChar;
        for (it = errorTableUp.begin(); it != errorTableUp.end(); it++) {
            bool isEnd = true;
            vector<int>::iterator it_right;
            for (it_right = rightTable.begin(); it_right != rightTable.end(); it_right++) {
                if ((*it) == (*it_right)) {
                    isEnd = false;
                    break;
                }
            }
            if (isEnd){
                errorChar = (*it);
                cout << errorChar << " is the counterfeit coin and it is light." << endl;
                break;
            }
        }
        for (it = errorTableDown.begin(); it != errorTableDown.end(); it++) {
            bool isEnd = true;
            vector<int>::iterator it_right;
            for (it_right = rightTable.begin(); it_right != rightTable.end(); it_right++) {
                if ((*it) == (*it_right)) {
                    isEnd = false;
                    break;
                }
            }
            if (isEnd) {
                errorChar = (*it);
                cout << errorChar << " is the counterfeit coin and it is heavy." << endl;
                break;
            }
        }
    }
}