1100.cpp

这是哈尔滨工业大学acmOJ的源代码

/*  This Code is Submitted by wywcgs for Problem 1100 on 2005-09-16 at 15:30:07 */ 
#include <stdio.h>

int main()
{
    char stack[260], ch;
    int top;
    
    while(1) {
        top = 0;
        while(1) {
            ch = getchar();
            if(ch == EOF) {
                return 0;
            } else if(ch == '\n') {
                break;
            } else {
                if((ch >= 'p') && (ch <= 'z')) {
                    stack[top++] = 1;
                    while(1) {
                        if((top >= 2) && (stack[top-2] == 2)) {
                            top -= 2;
                            stack[top++] = 1;
                        } else if((top >= 3) && (stack[top-2] == 1) && (stack[top-3] == 3)) {
                            top -= 3;
                            stack[top++] = 1;
                        } else {
                            break;
                        }    
                    }    
                } else if(ch == 'N') {
                    stack[top++] = 2;
                } else if((ch == 'C') || (ch == 'D') || (ch == 'E') || (ch == 'I')) {
                    stack[top++] = 3;
                } else {
                    stack[top++] = 0;
                }    
            }
        }
        if((top == 1) && (stack[0] == 1)) {
            printf("YES\n");
        } else {
            printf("NO\n");
        }    
    }
}