Longest Substring without Duplication

最新推荐文章于 2019-05-14 15:07:25 发布

原创最新推荐文章于 2019-05-14 15:07:25 发布 · 357 阅读

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本文介绍了一个算法，用于计算给定字符串中不包含重复字符的最长子串长度。通过定义子问题并使用特定函数实现，该算法有效地解决了这一挑战。

Problem: Given a string, please get the length of the longest substring which does not have duplicated characters. Supposing all characters in the string are in the range from ‘a’ to ‘z’.

妙处在于如何正确定义子问题。

参考：http://codercareer.blogspot.com/2013/11/no-49-longest-substring-without.html

/* Copyleft: Ming Lin <minggr@gmail.com> */

#include <stdio.h>

char *position(char *str, int len, char c)
{
	while (len > 0) {
		if (c == *str)
			return str;
		len--;
		str--;
	}

	return NULL;
}

int longest_substring(char *str)
{
	int len, maxlen;
	char *tmp;

	len = maxlen = 0;
	while (*str) {
		if (len == 0) {
			maxlen = len = 1;
			str++;
			continue;
		}
		tmp = position(str-1, len, *str);
		if (!tmp)
			len++;
		else
			len = str - tmp;
		if (len > maxlen)
			maxlen = len;
		str++;
	}

	return maxlen;
}

int main()
{
	char str[] = "abazckbLMNLb";

	printf("%s\n", str);
	printf("longest_substring: %d\n", longest_substring(str));
	return 0;
}