提供 SPJ

#include "testlib.h"
#include <bits/stdc++.h>
constexpr int dx[]={-1,1,0,0},dy[]={0,0,-1,1};
int r,c,n,cost,realcost,w[17][17],f[17][17];
int food;
std::string path;
std::deque<std::pair<int,int> > snake;
inline int getdir(char c){
	switch(c){
		case 'U':return 0;
		case 'D':return 1;
		case 'L':return 2;
		case 'R':return 3;
	}
	return -1;
}
int main(int argc, char *argv[]) {
	registerTestlibCmd(argc,argv);
	std::string jans = ans.readLine(),
				pans = ouf.readLine();
	while(!jans.empty()&&isspace(jans.back())) jans.pop_back();
	while(!pans.empty()&&isspace(pans.back())) pans.pop_back();
	if(pans!=jans) quitf(_wa,"The first line is wrong. Read '%s', expected '%s'.",pans.c_str(),jans.c_str());
	if(pans!="No solution."){
		cost=std::stoi(pans);
		if(cost>0){
			path=ouf.readToken();
			r=inf.readInt(),c=inf.readInt();
			if(path.size()>20000000u) quitf(_wa,"The path is too long.");
			for(int i{1};i<=r;++i){
				std::string _=inf.readToken();
				for(int j{1};j<=c;++j)
					w[i][j]=(_[j-1]&15);
			}
			for(int i{0};i<4;++i){
				int x=inf.readInt(),y=inf.readInt();
				snake.emplace_back(x,y);
			}
			n=inf.readInt();
			for(int i{0};i<n;++i){
				int x=inf.readInt(),y=inf.readInt();
				f[x][y]|=(1<<i);
			}
			for(int i{0};i<(int)path.size();++i){
				char c{path[i]};
				int d=getdir(c);
				if(d==-1)
					quitf(_wa,"On step %d, unknown direction character '%c'.\n",i+1,c);
				auto [x,y]=snake.front();
				int tx{x+dx[d]},ty{y+dy[d]};
				if(!(tx>=1&&tx<=r&&ty>=1&&ty<=c)) quitf(_wa,"The snake walked out of the map, on step %d.",i+1);
				if(!w[tx][ty]) quitf(_wa,"The snake walked on (%d,%d) whose W is 0, on step %d.",tx,ty,i+1);
				food|=f[tx][ty];
				snake.emplace_front(tx,ty);
				if((int)snake.size()>4+__builtin_popcount(food)) snake.pop_back();
				for(int j{1};j<(int)snake.size();++j)
					if(snake[0]==snake[j])
						quitf(_wa,"The snake walked on itself, on step %d.",i+1);
				realcost+=std::abs(w[x][y]-w[tx][ty])+1;
			}
			if(food!=(1<<n)-1)
				quitf(_wa,"The snake hasn't eaten all food.");
			if(realcost!=cost)
				quitf(_wa,"The cost of your path is %d, expected %d.",realcost,cost);
		}
		quitf(_ok,"Accepted. cost = %d.",cost);
	}
	else
		quitf(_ok,"Accepted. No solution.");
	return 0;
}