Package g0001_0100.s0045_jump_game_ii

Class Solution

java.lang.Object
g0001_0100.s0045_jump_game_ii.Solution
public class Solution extends Object
45 - Jump Game II.

Medium

You are given a 0-indexed array of integers nums of length n. You are initially positioned at index 0.

Each element nums[i] represents the maximum length of a forward jump from index i. In other words, if you are at index i, you can jump to any index (i + j) where:

  • 0 <= j <= nums[i] and
  • i + j < n

Return the minimum number of jumps to reach index n - 1. The test cases are generated such that you can reach index n - 1.

Example 1:

Input: nums = [2,3,1,1,4]

Output: 2

Explanation: The minimum number of jumps to reach the last index is 2. Jump 1 step from index 0 to 1, then 3 steps to the last index.

Example 2:

Input: nums = [2,3,0,1,4]

Output: 2

Constraints:

  • 1 <= nums.length <= 104
  • 0 <= nums[i] <= 1000
  • It’s guaranteed that you can reach nums[n - 1].

To solve the “Jump Game II” problem in Java with a Solution class, we can follow these steps:

  1. Define a Solution class.
  2. Define a method named jump that takes an array of non-negative integers nums as input and returns the minimum number of jumps required to reach the last index.
  3. Initialize variables maxReach, steps, and end to keep track of the maximum reachable position, the number of steps taken, and the end position respectively. Initialize maxReach to 0 and end to 0.
  4. Iterate through the array from index 0 to nums.length - 2:
    • Update maxReach as the maximum of maxReach and i + nums[i].
    • If the current index i equals end, update end to maxReach and increment steps.
  5. Return steps.

Here’s the implementation:

public class Solution {
    public int jump(int[] nums) {
        int maxReach = 0;
        int steps = 0;
        int end = 0;

        for (int i = 0; i < nums.length - 1; i++) {
            maxReach = Math.max(maxReach, i + nums[i]);
            if (i == end) {
                end = maxReach;
                steps++;
            }
        }

        return steps;
    }
}

This implementation provides a solution to the “Jump Game II” problem in Java. It calculates the minimum number of jumps required to reach the last index by iterating through the array and updating the maximum reachable position and the end position accordingly.

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • jump

      public int jump(int[] nums)