#124 Medium Time O(n) Space O(1) Animated

Jump Game II

Find the minimum number of jumps to reach the last index.

LeetCode ↗

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1 Predict
2 Trace
3 Explain
4 Implement

Pattern Greedy choice with a local proof

Commit to the locally best safe choice only after identifying why it cannot block an optimal answer.

Approach: Greedy (BFS-like)

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Core Insight

Commit to the locally best safe choice only after identifying why it cannot block an optimal answer.

Common Pitfall

Sort or define the selection order before applying the greedy rule.

Description

Find the minimum number of jumps to reach the last index.

Constraints

Time Complexity: O(n)
Space Complexity: O(1)

Solution — Greedy (BFS-like)

TimeO(n) SpaceO(1)

Implementation Plan

Translate the invariant into these small, testable moves.

Order candidates by the greedy criterion.
Inspect the next candidate.
Accept it only when it preserves feasibility.
Return the accumulated result.

def jump(nums):
    res = 0
    l = r = 0
    
    while r < len(nums) - 1:
        farthest = 0
        for i in range(l, r + 1):
            farthest = max(farthest, i + nums[i])
        l = r + 1
        r = farthest
        res += 1
        
    return res

Jump Game

Gas Station

Jump Game II

Steps

Description

Constraints

Tags

Solution — Greedy (BFS-like)