Leetcode 278: First Bad Version

leetcode_278.cpp

#include <iostream>

using namespace std;

//leetcode supplied function (I've created an example): 
bool isBadVersion(int n) {
    return (n >= 4);
}

int firstBadVersion(int n) {
    int l=1, r=n, m=l+(r-l)/2;
    while (l <= r) {
        m = l+(r-l)/2;
        if (isBadVersion(m)) r = m-1;  //go left
        else l=m+1;  //go right
    }
    if (!isBadVersion(m)) m++;  
    return m;
}

int main() {
    int n = 10;
    cout << firstBadVersion(n) << "\n";
    return 0;
}