Hello coders, today we are going to solve the Black & White Ring Game Codechef Solution whose Problem Code is RING_GAME.
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Black & White Ring Game Codechef Solution
Problem
Alice and Bob are playing a game. Alice goes first.
They have a binary circular array A with N elements. In one move, a player can:
- Choose a circular continuous segment of the array and perform a left cyclic shift on the chosen segment.
We define the term diff(A) as the number of pairs of adjacent elements with different values. Note that we also consider A_NAN and A_1A1 as adjacent.
A player can make a move only if, for the updated array A’A′, diff(A’)\gt diff(A)diff(A′)>diff(A).
The player who is unable to make a move, loses. Find the winner of the game if both players play optimally.
Note:
- For an array AA with NN elements, some circular continuous segments are [A_1], [A_1, A_2, A_3], [A_{N-1}, A_N, A_1, A_2][A1],[A1,A2,A3],[AN−1,AN,A1,A2], etc.
- A left cyclic shift of a segment [A_1, A_2, A_3][A1,A2,A3] is [A_2, A_3, A_1][A2,A3,A1]. Similarly, left cyclic shift of segment [A_{N-1}, A_N, A_1, A_2][AN−1,AN,A1,A2] is [A_N, A_1, A_2, A_{N-1}][AN,A1,A2,AN−1].
Input Format
- The first line of input contains a single integer TT, the number of test cases. The description of the test cases follows.
- Each test cases consists of two lines of input.
- The first line of each test case contains a single integer NN, the number of elements.
- The second line of each test case contains NN space-separated integers A_1,A_2, \ldots, A_NA1,A2,…,AN.
Output Format
For each test case, if Alice will win print Alice
, otherwise print Bob
.
You may print each character in Uppercase or Lowercase. For example: BOB
, bob
, boB
, and Bob
are all identical.
Constraints

Sample 1
Input
3 3 1 0 1 4 1 1 0 0 8 1 0 1 0 0 0 1 1
Output
Bob
Alice
Bob
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Explanation:
Test case 1: Alice can not perform any move. Thus, Bob wins.
Test case 2: Alice can perform the following move:
- Choose the segment [A1,A2,A3] and perform left cyclic shift. Thus, A becomes [1,0,1,0].
Also, diff([1,1,0,0])=2 as pairs of adjacent elements with different values are (A_2, A_3) and (A4,A1). After this move, diff([1,0,1,0])=4 as all pairs of adjacent elements have different values. Since diff([1, 1, 0, 0]) diff([1,1,0,0]), this move is valid.
After performing the move, Bob has no valid move left. Thus, Alice wins.
Black & White Ring Game Codechef Solution in CPP
#include <bits/stdc++.h> using namespace std; #define mp make_pair #define f first #define mt make_tuple #define s second #define ll long long #define NO cout << "NO" << '\n' #define YES cout << "YES" << '\n' #define rep(i, a, b) for(int i = a; i < (b); ++i) typedef pair<int, int> pii; typedef vector<int> vi; typedef map<int,int> mii; class comp{ public: bool operator()(pair<int,int>&t,pair<int,int>&c){ return t.f > c.f; } }; class comp_2{ public: bool operator()(pair<int,int>&t,pair<int,int>&c){ return t.s > c.s; } }; int main() { int test; ios_base::sync_with_stdio(false); cin.tie(NULL); cin >> test; rep(i, 0, test) { int n; cin >> n; if (n==1){ cout << "Bob" << '\n'; continue; } vi arr(n); rep(j,0,n) { cin >> arr[j]; } int dif = 0; int one = 0; int z = 0; if (arr[0]==arr[n-1]){ if (arr[0]){ one++; } else { z++; } } int p = 1; while (p < n){ if (arr[p]==arr[p-1]){ if(arr[p]){ one++; } else { z++; } } p++; } dif = min(z,one); if (dif%2==0){ cout << "Bob" << '\n'; } else { cout << "Alice" << '\n'; } } }
Black & White Ring Game Codechef Solution in JAVA
import java.util.*; import java.lang.*; class credsits { public static void main (String[] args) { Scanner scan = new Scanner(System.in); int cases = scan.nextInt(); for(int c = 0; c< cases ;c++){ int[] array = new int[scan.nextInt()]; for(int i = 0; i<array.length;i++){ array[i] = scan.nextInt(); } if(array.length==1 ||array.length == 2){ System.out.println("Bob"); return; } int one = 0; int zero = 0; int counter = 0; for(int i = 0; i<array.length;i++){ if(array[i]==0)zero++; else one++; if(i!=array.length-1) { if (array[i] != array[i + 1]) counter++; }else if(array[i]!=array[0])counter++; } int max = 2*Math.min(one,zero); if(((max-counter)/2)%2==0 )System.out.println("Bob"); else System.out.println("Alice"); } } }
Black & White Ring Game Codechef Solution in Python
# Chase2learn # cook your dish here for _ in range(int(input())): n = int(input()) l = list(map(int, input().split())) a = 0 b = 2 * min(l.count(0), l.count(1)) for i in range(n): if l[i] != l[i - 1]: a += 1 if ((b - a) // 2) % 2 == 0: print('Bob') else: print('Alice')
Disclaimer: The above Problem (Black & White Ring Game) is generated by CodeChef but the solution is provided by Chase2learn.This tutorial is only for Educational and Learning purpose.
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