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233. Number of Digit One(統計1出現的次數)

BE question because cti action git scrip ase pear

Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n.

For example:
Given n = 13,
Return 6, because digit 1 occurred in the following numbers: 1, 10, 11, 12, 13.

按不同位置統計

31456 統計百位時:

(0-31) 1 (0-99) 32*100次

31156:

(0-30)1(0-99) + (31) 1 (0-56) 31*100+56+1次

31056:

(0-30)1 (0-99) _31*100 次

233. Number of Digit One(統計1出現的次數)