Majority-Element-D&C

#include <iostream>
#include <vector>

using namespace std;

int majority(vector<int>& A, int l, int r) {
    if (l == r) {
        return A[l];
    }
    int mid = (l + r) / 2;
    int a = majority(A, mid + 1, r);
    int b = majority(A, l, mid);
    if (a == b) {
        return a;
    }
    int count_a = 0;
    int count_b = 0;
    for (int i = l; i <= r; i++) {
        if (A[i] == a) {
            count_a += 1;
        } else if (A[i] == b) {
            count_b += 1;
        }
    }
    if (count_a > (r - l + 1) / 2) {
        return a;
    } else if (count_b > (r - l + 1) / 2) {
        return b;
    } else {
        return -1; // Not found
    }
}

int main() {
    vector<int> A = {2, 2, 3, 4, 2, 2, 5};
    int l = 0;
    int r = A.size() - 1;
    int result = majority(A, l, r);
    if (result != -1) {
        cout << "Majority element: " << result << endl;
    } else {
        cout << "No majority element found." << endl;
    }
    return 0;
}