2 posts tagged with "Math"

Question description​

You are given a string $S$ of length $N$, consisting of only lowercase English letters.

Find the lexicographically smallest substring of $S$ with a length of $K$ and output it.

Note:
A substring of a string $T$ is a string obtained by removing 0 or more characters from $T$ and concatenating the remaining characters in their original order.

The definition of lexicographic order:
Let $X = x_1 x_2 \dots x_n$ and $Y = y_1 y_2 \dots y_m$ be two different strings. $X$ is said to be lexicographically smaller than $Y$ if and only if $X$ is a prefix of $Y$, or if $j$ is the smallest integer such that $x_j \neq y_j$, and $x_j < y_j$.

Question description​

You are given a set of digits: $c_1, c_2, \dots, c_K$. Find the number of positive integers with $N$ digits that can be created using only these digits and are divisible by $B$. Calculate the result modulo $10^9 + 7$.