Codeforces 1741E Sending a Sequence - Determining the Final Answer

$dp[i] = \text{false} \quad \text{for all } i \ge 1 \text{ initially}.$

$4.$ Determine the final answer

Here the fourth step is also simple: if the whole array can be split into valid blocks, then the answer is YES if $dp[n] = \text{true}$, and NO otherwise.

So the only missing piece is the transition (how $dp[i]$ depends on earlier dp values). Before moving to the next unit, try to think: given this definition of $dp[i]$, how do you find which earlier states matter?