递归
注意:The input consists of a number of sentences consisting only of characters p through z and N, C, D, E, and I.这句话是错的,句子还会包含不合法字符。
View Code
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;
#define maxl 500
char st[maxl];
int find(char *st)
{
if (st[0] <= 'z' && st[0] >= 'p')
return 1;
if (st[0] == 'N')
{
int x = find(st + 1);
if (x == -1)
return x;
return 1 + x;
}
if (st[0] == 'I' || st[0] == 'D' || st[0] == 'E' || st[0] == 'C')
{
int x = find(st + 1);
if (x == -1)
return x;
int y = find(st + 1 + x);
if (y == -1)
return x;
return 1 + x + y;
}
return -1;
}
int main()
{
//freopen("t.txt", "r", stdin);
while (scanf("%s", st) == 1)
{
if (find(st) == (signed int)strlen(st))
printf("YES\n");
else
printf("NO\n");
}
return 0;
}