Package g1101_1200.s1155_number_of_dice_rolls_with_target_sum

Class Solution

java.lang.Object

g1101_1200.s1155_number_of_dice_rolls_with_target_sum.Solution

public class Solution
extends Object

1155 - Number of Dice Rolls With Target Sum.<p>Medium</p> <p>You have <code>n</code> dice and each die has <code>k</code> faces numbered from <code>1</code> to <code>k</code>.</p> <p>Given three integers <code>n</code>, <code>k</code>, and <code>target</code>, return <em>the number of possible ways (out of the</em> <code>kⁿ</code> <em>total ways)</em> <em>to roll the dice so the sum of the face-up numbers equals</em> <code>target</code>. Since the answer may be too large, return it <strong>modulo</strong> <code>10⁹ + 7</code>.</p> <p><strong>Example 1:</strong></p> <p><strong>Input:</strong> n = 1, k = 6, target = 3</p> <p><strong>Output:</strong> 1</p> <p><strong>Explanation:</strong> You throw one die with 6 faces.</p> <p>There is only one way to get a sum of 3.</p> <p><strong>Example 2:</strong></p> <p><strong>Input:</strong> n = 2, k = 6, target = 7</p> <p><strong>Output:</strong> 6</p> <p><strong>Explanation:</strong> You throw two dice, each with 6 faces.</p> <p>There are 6 ways to get a sum of 7: 1+6, 2+5, 3+4, 4+3, 5+2, 6+1.</p> <p><strong>Example 3:</strong></p> <p><strong>Input:</strong> n = 30, k = 30, target = 500</p> <p><strong>Output:</strong> 222616187</p> <p><strong>Explanation:</strong> The answer must be returned modulo 10⁹ + 7.</p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= n, k <= 30</code></li> <li><code>1 <= target <= 1000</code></li> </ul>

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
int	numRollsToTarget(int n, int k, int target)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Solution

public Solution()

Method Details

numRollsToTarget

public int numRollsToTarget(int n,
 int k,
 int target)