1.7-02：找第一个只出现一次的字符

#include<iostream>
#include<string>
#define N 100000
using namespace std;
int main()
{
	int i = 0, j = 0, k = 1, e, f = 0;
	char a = '?';
	char str[N];
	cin >> str;
	for (i = 0; a != '\0'; i++)
	{
		a = str[i];
	}
	e = i;
	for (i = 0; i < e - 1; i++)
	{
		a = str[i];
		for (j = 0; j < e; j++)
		{
			if (a == str[j])
			{
				k++;
			}
		}
		if (k == 2)
		{
			cout << a << endl;
			f += k;
			break;
		}
		k = 1;
	}
	if (f == 0)
	{
		cout << "no" << endl;
	}
	return 0;
}