The version number of positive expressions

Verify the version number of regular expressions,
requirements, must be three, in the form of xxx,
the scope of each x respectively 1-99,0-99,0-99.
Without allowing the 0.xx; 01.xx; x.0x.x; x.00.x; xx00; xx0x
satisfying these conditions was positive: ^ ([1-9] \ d | [1-9]) (. ([1-9] \ d | \ d)) {2} $

Reprinted from: https://www.jianshu.com/p/12700af9fcb7