1. Farthest reach
Track the farthest index reachable so far.
let reach = 0Typorithm · medium
Jump Game
▷ Interactive algorithm labjump-gamegreedyreachabilityfarthest-reachgreedy-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
Greedy
Walk left to right, tracking the farthest reachable index; fail the moment an index is unreachable.
Each value tells you the maximum jump length from that index.
The greedy insight is that only the farthest reach matters, not which exact jumps you take.
If you ever stand on an index beyond the farthest reach, the last index is impossible.
Preparing algorithm lab…
01
Track one number: the farthest reach.
02
Fail if i passes reach.
03
reach = max(reach, i + nums[i]).
function canJump(nums) {
let reach = 0;
for (let i = 0; i < nums.length; i += 1) {
if (i > reach) {
return false;
}
reach = Math.max(reach, i + nums[i]);
}
return true;
}Read the implementation
Connect each part of the code to the concept before you type.
2. Scan indexes
Walk every index from left to right.
for (let i = 0; i < nums.length; i += 1)3. Unreachable
If the current index is past the farthest reach, it can never be reached.
if (i > reach)4. Extend reach
From index i you can reach i + nums[i]; keep the farthest.
reach = Math.max(reach, i + nums[i])A 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.