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📚 Jump Game II – Java Cheat Sheet

📌 What Is It?

The Jump Game II problem involves finding the minimum number of jumps required to reach the last index of an array. Each element in the array represents the maximum jump length at that position.

🧱 Pattern Template

Greedy Algorithm

class Solution {
    public int jump(int[] nums) {
        int jumps = 0, currentEnd = 0, farthest = 0;

        for (int i = 0; i < nums.length - 1; i++) {
            farthest = Math.max(farthest, i + nums[i]);

            if (i == currentEnd) {
                jumps++;
                currentEnd = farthest;

                if (currentEnd >= nums.length - 1) {
                    break;
                }
            }
        }

        return jumps;
    }
}

▶️ View Animation

📊 Time Complexity

• Time Complexity: O(N), where N is the length of the array.
• Space Complexity: O(1), as no additional space is used.

✅ Use Cases

• Solving problems involving minimum steps or jumps in arrays.
• Optimizing traversal in linear structures.

📘 Common LeetCode Problems

• 45. Jump Game II [Medium] Greedy

🧪 Example

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

Explanation:
- Jump 1 step from index 0 to index 1.
- Then jump 3 steps to the last index.

💡 Pro Tips

• Use a greedy approach to always jump to the farthest reachable index.
• Track the current jump range (`currentEnd`) and update it when the range is exhausted.
• Break early if the last index is reachable within the current jump.