题目
请编写递归算法, 逆转广义表中的数据元素。例如: 将广义表:
(a,((b,c),()),(((d),e),f))
逆转为:((f,(e,(d))),((),(c,b)),a)
。
代码
#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
void reverse_str(char *s, int l, int r)
{
int n = r-l;
for (int i = 0; i < n/2; ++i)
swap(s[l+i], s[l+(n-1-i)]);
}
void reverse_list_recur(char *s, int l, int r)
{
int i = l, last_i = l;
int c1 = 0, c2 = 0;
do {
if (s[i] == '(') ++c1;
else if (s[i] == ')') ++c2;
if ((c1 == c2+1 && s[i] == ',') || (c1 == c2 && s[i] == ')')) {
reverse_list_recur(s, last_i+1, i);
reverse_str(s, last_i+1, i);
last_i = i;
}
++i;
} while (c1 != c2);
reverse_str(s, l+1, r-1);
}
int main()
{
char s[] = "(a,((b,c),()),(((d),e),f))";
reverse_list_recur(s, 0, strlen(s));
cout << s << endl;
system("pause");
return 0;
}