Given a $0$-indexed string num of length n consisting of digits, determine if for every index i from $0$ to n - 1, the digit i appears exactly num[i] times in num.

Return true if this condition holds for all indices, or false otherwise.

Constraints:

• n == num.length

• $1 \leq$ n $\leq 10$

• num consists of digits.

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We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

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