编程算法

第一个仅仅出现一次的字符 代码(C)

本文地址: http://blog.csdn.net/caroline_wendy

题目: 在字符串中找出第一个仅仅出现一次的字符.

字符是char类型, 所以匹配256种可能, 採用hash表, 计算出现的次数, 再找到第一次出现的字符.

代码:

/*
 * main.cpp
 *
 *  Created on: 2014.6.12
 *      Author: Spike
 */

/*eclipse cdt, gcc 4.8.1*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char FirstNotRepeatingChar (char* pString) {
	if (pString == NULL)
		return '';
	const int tableSize = 256;
	unsigned int hastTable[tableSize];
	for (unsigned int i=0; i<tableSize; ++i)
		hastTable[i] = 0;
	char* pHashKey = pString;
	while (*pHashKey != '')
		hastTable[*(pHashKey++)]++;
	pHashKey = pString;
	while (*pHashKey != '') {
		if (hastTable[*pHashKey] == 1)
			return *pHashKey;
		pHashKey++;
	}
	return '';
}

int main(void)
{
	char pString[] = "abaccdeff";
	char result =  FirstNotRepeatingChar (pString);
    printf("result = %c
", result);

    return 0;
}

输出:

result = b