Freaks City

Problem Analysis: Digit DP Before explaining the correct solution, let's first discuss the partial score approach. For 50% of the data, where (1 \le L, R \le 10^6), a brute force simulation might be feasible. However, since we don't know the exact positions where each number appears, directly simulating with a 2D array is likely to cause memory ...

When solving counting problems over large numerical ranges, traditional anumeration becomes inefficient due to redundant computations. Consider counting processes from 7000 to 7999, 8000 to 8999, and 9000 to 9999. These intervals share a common pattern: the lower three digits cycle from 000 to 999, with only the thousand's digit varying. This o ...