merge.py

def merge_ranges(input_range_list):
    prev_start_date = input_range_list[0][0]
    prev_end_date = input_range_list[0][1]
    result = []
    for i in range(1,len(input_range_list)):
        current_start_date = input_range_list[i][0]
        if current_start_date > prev_end_date:
            result.append([prev_start_date,prev_end_date])
            prev_start_date = current_start_date
            prev_end_date = input_range_list[i][1]
        else:
            prev_end_date = max(prev_end_date,input_range_list[i][1])

    result.append([prev_start_date,prev_end_date])
    return result

print merge_ranges([[5,50], [25,100], [150,200]])