ZOJ 1056 The Worm Turns

原题链接

题目大意：贪吃蛇的简化版，给出一串操作命令，求蛇的最终状态是死是活。

解法：这条蛇一共20格的长度，所以用一个20个元素的队列表示，队列的每个元素是平面的坐标。每读入一条指令，判断其是否越界，是否咬到了自己。若都没有，把改点压入队列，front元素弹出。

参考代码：

#include<iostream>
#include<queue>
#include<string>
using namespace std;

struct Point{
	int r;
	int c;
};

queue<Point> worm;

bool isItself(queue<Point>,Point);

int main(){
	int i,n;
	char str[102];
	Point temp;
	char x;
	while(cin>>n&&n!=0){
		while(!worm.empty())
			worm.pop();
		for(i=11;i<=30;i++){
			temp.c=i;
			temp.r=25;
			worm.push(temp);
		}
		cin>>str;
		i=1;
		while(i<=n){
			x=str[i-1];
			temp=worm.back();
			if(x=='W'){
				temp.c-=1;
				if((temp.c)<1){
					cout<<"The worm ran off the board on move "<<i<<'.'<<endl;
					break;
				}
				if(isItself(worm,temp)){
					cout<<"The worm ran into itself on move "<<i<<'.'<<endl;
					break;
				}
				worm.push(temp);
				worm.pop();

			}else{
				if(x=='E'){
					temp.c+=1;
					if((temp.c)>50){
						cout<<"The worm ran off the board on move "<<i<<'.'<<endl;
						break;
					}
					if(isItself(worm,temp)){
						cout<<"The worm ran into itself on move "<<i<<'.'<<endl;
						break;
					}
					worm.push(temp);
					worm.pop();
				}else{
					if(x=='S'){
						temp.r+=1;
						if((temp.r)>50){
							cout<<"The worm ran off the board on move "<<i<<'.'<<endl;
							break;
						}
						if(isItself(worm,temp)){
							cout<<"The worm ran into itself on move "<<i<<'.'<<endl;
							break;
						}
						worm.push(temp);
						worm.pop();
					}else{
						if(x=='N'){
							temp.r-=1;
							if((temp.r)<1){
								cout<<"The worm ran off the board on move "<<i<<'.'<<endl;
								break;
							}
							if(isItself(worm,temp)){
								cout<<"The worm ran into itself on move "<<i<<'.'<<endl;
								break;
							}
							worm.push(temp);
							worm.pop();
						}
					}
				}
			}

	
			if(i==n)
				cout<<"The worm successfully made all "<<n<<" moves."<<endl;
			i++;
		}
	}
	
	return 0;
}

bool isItself(queue<Point> worm,Point p){
	int k;
	queue<Point> w;
	w=worm;
	w.pop();
	for(k=1;k<19;k++){
		if(w.front().r==p.r&&w.front().c==p.c)
			return true;
		w.pop();
	}
	return false;
}