Discussions

Clean Python solution, beats most submissions. Define dp[i] as the answer for the first i elements and write the transition from smaller states. Once it works, notice you only need the previous row/value, so space drops to O(1) or O(n).

Finally got AC after 3 WAs. Sharing what I missed. Define dp[i] as the answer for the first i elements and write the transition from smaller states. Once it works, notice you only need the previous row/value, so space drops to O(1) or O(n).

Finally got AC after 3 WAs. Sharing what I missed. Define dp[i] as the answer for the first i elements and write the transition from smaller states. Once it works, notice you only need the previous row/value, so space drops to O(1) or O(n).