diff options
Diffstat (limited to 'num_dice_roll_target_sum.py')
-rw-r--r-- | num_dice_roll_target_sum.py | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/num_dice_roll_target_sum.py b/num_dice_roll_target_sum.py new file mode 100644 index 0000000..42bf247 --- /dev/null +++ b/num_dice_roll_target_sum.py @@ -0,0 +1,37 @@ +# 1155. Number of Dice Rolls With Target Sum + +""" +you have 'n' dice and die has 'k' faces numbered 1 to 'k'. given three +integers 'n', 'k', and 'target', return the number of possible ways to roll +the dice so the sum of the face up numbers equals 'target'. since the answer +may be too large, return it modulo 10e9+7 +""" + + +class Solution(object): + def numRollsToTarget(self, n, k, target): + """ + :type n: int + :type k: int + :type target: int + :rtype: int + """ + mod = 10**9 + 7 + prev = [0] * (target + 1) + curr = [0] * (target + 1) + for i in range(1, n + 1): + for j in range(1, target + 1): + ans = 0 + for x in range(1, k + 1): + if j - x >= 0: + ans += prev[j - x] % mod + curr[j] = ans + prev = curr[:] + return int(prev[target] % mod) + + +if __name__ == "__main__": + obj = Solution() + print(obj.numRollsToTarget(1, 6, 3)) + print(obj.numRollsToTarget(2, 6, 7)) + print(obj.numRollsToTarget(30, 30, 500)) |