Debug用 #ifndef ONLINE_JUDGE freopen("848_input.txt", "r",stdin); freopen("848_output.txt","w",stdout); #endif 進階版getch(), ungetch() (from K&R) // ungetch(): push a char to stack // getch(): if stack is not empty, pop a char // or get a char from stdin. int buffer[1024]; int top = -1; //stack pointer void ungetch(int c){ buffer[++top] = c; } int getch(){ if(top > -1) return buffer[top--]; else return getchar(); }