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Jump Game II

Explore the Jump Game II problem where you calculate the minimum number of jumps to reach the last index of an array. Understand how to apply greedy techniques for an optimal O(n) time and O(1) space solution. This lesson helps you develop and implement the logic to solve the problem efficiently.

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Statement

In a single player jump game, the player starts at one end of a series of squares and aims to reach the last square.

At each turn, the player can take up to ss steps toward the last square, where ss is the value of the current square.

For example, if the value of the current square is 33, the player can take either 33 steps, 22 steps, or 11 steps in the direction of the last square. The player cannot move in the opposite direction, away from the last square.

You’ve been provided with the nums integer array, representing the series of squares.

You’re initially positioned at the first index of the array. Find the minimum number of jumps needed to reach the last index of the array.

You may assume that you can always reach the last index.

Constraints

  • 1≤1 \leq nums.length ≤103\leq 10^3

  • 0≤0\leq nums[i] ≤103\leq 10^3

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Jump Game II

1.

What is the minimum number of jumps required to reach the end of the array if we start from the first element?

array = [1, 2, 3, 4, 5]

A.

3

B.

5

C.

1

1 / 2

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Note: As an additional challenge, we have intentionally hidden the solution to this puzzle.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3
4
5

Try it yourself

Implement your solution in the following coding playground.

We have left the solution to this challenge as an exercise for you. The optimal solution to this problem runs in O(n) time and takes O(1) space. You may try to translate the logic of the solved puzzle into a coded solution.

Java
usercode > Solution.java
import java.util.*;
public class Solution{
   public static int jumpGame2(int[] nums) {
      
      // Replace this placeholder return statement with your code
      return 0;
   }
}
Jump Game II