maxSubArray.py

# Using Kadane's algorithm

def max_subarray(numbers):
    """Find a contiguous subarray with the largest sum."""
    best_sum = 0  # or: float('-inf')
    best_start = best_end = 0  # or: None
    current_sum = 0
    for current_end, x in enumerate(numbers):
        if current_sum <= 0:
            # Start a new sequence at the current element
            current_start = current_end
            current_sum = x
        else:
            # Extend the existing sequence with the current element
            current_sum += x

        if current_sum > best_sum:
            best_sum = current_sum
            best_start = current_start
            best_end = current_end + 1  # the +1 is to make 'best_end' exclusive

    return best_sum, best_start, best_end