MEDIUM NC#124 Greedy / BFS
45. Jump Game II
📖 Problem
You are given a 0-indexed array of integers nums of length n. You are initially positioned at nums[0]. Each element nums[i] represents the maximum jump length at that position. Return the minimum number of jumps to reach nums[n - 1]. The test cases are generated such that you can reach nums[n - 1].
🧠 Visual Learning Aid
1 Model the input into the right structure
2 Choose the core technique and invariant
3 Execute step-by-step with a sample
4 Validate complexity and edge cases
JS/TS Refreshers
- •Array methods (`push`, `pop`, `shift`, `slice`)
- •Object/Map/Set usage patterns
- •Function parameter and return typing
- •Level-order traversal
- •Queue discipline
- •Shortest-step interpretation
Logical Thinking Concepts
- •Define invariants before coding
- •Check edge cases first (`[]`, single element, duplicates)
- •Estimate time/space before implementation
- •Apply BFS reasoning pattern
- •Apply Greedy reasoning pattern
💡 Approach
- → Track the farthest reachable position in current jump
- → When current index equals the end of current jump's range, increment jump count
- → Time: O(n), Space: O(1)
🛠️ Hints & Pitfalls
Hints
- •Track the farthest reachable position in current jump
- •When current index equals the end of current jump's range, increment jump count
- •Time: O(n), Space: O(1)
🧪 Test Cases
Hidden tests on submit: 1
Test Case 1
Not run Input:
jump([2,3,1,1,4]); Expected:
2 Test Case 2
Not run Input:
jump([2,3,0,1,4]); Expected:
2 Test Case 3
Not run Input:
jump([0]); Expected:
0 📝 Code Editor
📤 Output