Package g0401_0500.s0403_frog_jump

Class Solution

java.lang.Object
g0401_0500.s0403_frog_jump.Solution
public class Solution extends Object
403 - Frog Jump.<p>Hard</p> <p>A frog is crossing a river. The river is divided into some number of units, and at each unit, there may or may not exist a stone. The frog can jump on a stone, but it must not jump into the water.</p> <p>Given a list of <code>stones</code>&rsquo; positions (in units) in sorted <strong>ascending order</strong> , determine if the frog can cross the river by landing on the last stone. Initially, the frog is on the first stone and assumes the first jump must be <code>1</code> unit.</p> <p>If the frog&rsquo;s last jump was <code>k</code> units, its next jump must be either <code>k - 1</code>, <code>k</code>, or <code>k + 1</code> units. The frog can only jump in the forward direction.</p> <p><strong>Example 1:</strong></p> <p><strong>Input:</strong> stones = [0,1,3,5,6,8,12,17]</p> <p><strong>Output:</strong> true</p> <p><strong>Explanation:</strong> The frog can jump to the last stone by jumping 1 unit to the 2nd stone, then 2 units to the 3rd stone, then 2 units to the 4th stone, then 3 units to the 6th stone, 4 units to the 7th stone, and 5 units to the 8th stone.</p> <p><strong>Example 2:</strong></p> <p><strong>Input:</strong> stones = [0,1,2,3,4,8,9,11]</p> <p><strong>Output:</strong> false</p> <p><strong>Explanation:</strong> There is no way to jump to the last stone as the gap between the 5th and 6th stone is too large.</p> <p><strong>Constraints:</strong></p> <ul> <li><code>2 <= stones.length <= 2000</code></li> <li><code>0 <= stones[i] <= 2<sup>31</sup> - 1</code></li> <li><code>stones[0] == 0</code></li> <li><code>stones</code> is sorted in a strictly increasing order.</li> </ul>

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • canCross

      public boolean canCross(int[] stones)