Solution:
Just a very simple DP. The hardest part is understanding the problem description and understanding the sample data.
We define $next$ to represent the corresponding index which is calculated according to $t$. For example $\lceil{i+x}\rceil$和$\lceil{i\cdot{x}}\rceil$。
For $cas$th operation. we have $ans[next]=cas$ and $used[next]=used[i]+1$ if $ans[i]\neq{-1}$ and $used[i]<y$. (Note that $used$ will be reset before each operation)
Scan and update $ans$与$used$. The scan order depends on if $next$ is larger than $i$ or not. May scan from left to right or scan from right to left.
That's all.
Code:
Submission #113021399 - Codeforces
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