Bubble Sort

BubbleSort.cpp

void bubbleSort(vector<int>& arr)
{   
    int lastIndex = arr.size() - 1;
    
    // n-1 passes
    for(int i = 0; i < lastIndex; i++){
        
        bool swapped = false;
        
        // from first element to last/secondLast/thirdLast element depending on pass count.
        for(int j = 0; j < lastIndex - i; j++){
            // swap if j-th element is more than j+1-th index.
            if(arr[j] > arr[j+1]){
                swap(arr[j], arr[j+1]);
                swapped = true;
            }
        }
        
        // if array is already sorted.
        if(!swapped)
            break;
        
    }
}