I don't want to be embarassed #2

Computer Science Level 4

Not again! This time, the Mathematician was tasked to perform in front of children. The mathematician had to think of a new trick but this time, his trick requires programming rather than mathematical knowledge.

This is the classic trick of cups and a ball. The cups are placed such that Cup 0 is placed at Position 0, Cup 1 placed at Position one...Cup $n$ is placed at Position $n$ . You are given that there are a total of 8 cups and 8 positions. The Mathematician wanted to confuse the children by changing the positions of the cups 41 times.

In the attached link, there are 41 lines of 2 integers(space separated). The first integer, $x$ represents Postion $x$ and the second integer $y$ represents Position $y$ . This line means that the cup at Position $x$ changes positions with the cup at Position $y$ . Therefore Cup originally at Position $x$ is now at Position $y$ and vice versa.

Given that the ball was originally under Cup 0 (i.e. Position 0). What position would it be in after the 41 swaps.

Example If we have 4 cups, Cup 0, Cup 1, Cup 2, Cup 3, and we are given 3 swaps:

0 2

1 3

2 3

The order now of the four cups are: 2 3 1 0

After swap 1: 2 1 0 3

After swap 2: 2 3 0 1

After swap 3: 2 3 1 0

Remember: The position is of the first cup is 0!

Attached link : Click here

0 4 5 7

1 solution

Daniel Lim
Aug 4, 2014

Here's my code in

C++

#include <iostream>
#include <stdio.h>
#include <vector>
#include <algorithm>
using namespace std;

int main(){

    freopen("problem.txt", "r", stdin);
    freopen("answer.txt", "w", stdout);

    vector <int> cups(41);
    for (int i = 0; i < 41; i++){
        cups[i] = i;
    }

    for (int i = 0; i < 41; i++){
        int x, y; cin >> x >> y;

        swap(cups[x], cups[y]);
    }

    for (int i = 0; i < 41; i++){
        if (cups[i] == 0){
            cout << i;
            break;
        }
    }
    return 0;
}

I don't want to be embarassed #2

1 solution

C++

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