1. Level boundary
end marks the farthest index reachable with the current number of jumps.
let end = 0Typorithm · hard
Jump Game II
▷ Interactive algorithm labjump-game-iigreedymin-jumpslevel-rangegreedy-choice
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Full lesson · 8 learning steps Open any exercise for focused practice
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Step 1 of 8 · intro card
Learn Jump Game II
Greedy
Treat each jump as a BFS level: count a jump each time you exhaust the current reachable range.
Jump Game II asks for the fewest jumps to reach the last index, not just whether it is reachable.
Each 'level' is the range of indexes reachable with the current jump count, like a BFS frontier.
When the scan hits the end of the current level, you must spend one jump and extend to the farthest seen.
Preparing algorithm lab…
01
Levels behave like BFS frontiers.
02
Bump jumps when i === end.
03
Loop stops before the last index.
function minJumps(nums) {
let jumps = 0;
let end = 0;
let farthest = 0;
for (let i = 0; i < nums.length - 1; i += 1) {
farthest = Math.max(farthest, i + nums[i]);
if (i === end) {
jumps += 1;
end = farthest;
}
}
return jumps;
}Read the implementation
Connect each part of the code to the concept before you type.
2. Extend frontier
Track the farthest index reachable from anywhere in the current level.
farthest = Math.max(farthest, i + nums[i])3. Level exhausted
When i reaches the level boundary, one more jump is forced.
if (i === end)4. Next level
The new boundary is the farthest we discovered this level.
end = farthestA complete learning loop
01
Understand
Read the concept map and follow the code breakdown.
02
Reconstruct
Type the implementation, repair mistakes and work through every recall exercise.
03
Verify
Use the final check without hints; revisit weak concepts in short practice sessions.