diff options
Diffstat (limited to 'users/wpcarro/scratch/facebook/knapsack-faq.py')
-rw-r--r-- | users/wpcarro/scratch/facebook/knapsack-faq.py | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/users/wpcarro/scratch/facebook/knapsack-faq.py b/users/wpcarro/scratch/facebook/knapsack-faq.py new file mode 100644 index 000000000000..ae04f5eb96c0 --- /dev/null +++ b/users/wpcarro/scratch/facebook/knapsack-faq.py @@ -0,0 +1,42 @@ +from utils import get, init_table, print_table + +# This problem has a few variants: +# - limited supply of each item +# - unlimited supply of each item +# - fractional amounts of each item (e.g. rice) + +def max_haul(capacity, items): + min_kg = min([kg for _, kg in items]) + max_kg = max([kg for _, kg in items]) + + cols = int(max_kg / min_kg) + fr_col_index = lambda index: min_kg * index + min_kg + to_col_index = lambda capacity: int((capacity - min_kg) * cols / max_kg) + + table = init_table(rows=len(items), cols=cols, default=0) + for row in range(len(table)): + for col in range(len(table[row])): + curr_capacity = fr_col_index(col) + value, kg = items[row] + + if kg > curr_capacity: + a = 0 + else: + a = value + get(table, row - 1, to_col_index(curr_capacity - kg)) + + b = get(table, row - 1, col) + table[row][col] = max([a, b]) + print_table(table) + return table[-1][-1] + +guitar = (1500, 1) +stereo = (3000, 4) +laptop = (2000, 3) +necklace = (2000, 0.5) +items = [necklace, guitar, stereo, laptop] +capacity = 4 +result = max_haul(capacity, items) +expected = 4000 +print(result, expected) +assert result == expected +print("Success!") |