Finds the first occurrence of a character in a string

Turn!

Problem:

Given a string, such as a = "ABCDACD", to find the first occurrence of a character, in a, the first occurrence of a character is ' B '.

Analysis:

In order to determine whether a character appears once, we can traverse from the beginning, and if there is no repetition, then choose, otherwise discard. The complexity of doing so is O (n^2). In fact, the question of whether the existence or the number of occurrences of the problem, basically will be related to hastable, we can build an array of array[256] (ASCII), and then the string first processed, for each occurrence of the character, we can be in the corresponding position +1. In this way, we iterate through the string again from the beginning, and if we find that the number of characters is 1, the character is returned.

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Finds the first occurrence of a character in a string