夜深人靜寫算法——佈線問題（廣搜bfs）

一：

 問題描述，求從a走到b的最短路徑

 #include <iostream>
 #include <cstring>
 #include <queue>
 #include <cstdlib>
 using namespace std;
 int dir[4][2] = {1,0,-1,0,0,1,0,-1};
  const int maxn = 100;
 class Position{	
	public:
		Position(int a,int b){
 			r = a,c = b;
		}
		friend bool FindPath(Position &start,Position &finish,int p[maxn][maxn]);
 		int r;
 		int c;
 	
 };
 bool FindPath(Position &start,Position &finish,int p[maxn][maxn]){
 	queue<Position>Q;
 	Q.push(start);
 	p[start.r][start.c] = 1;
 	
 	cout<<start.r<<endl;
 	cout<<start.c<<endl;
 	cout<<finish.r<<endl;
 	cout<<finish.c<<endl;
 	for(int i = 0; i <= 10;i++){
 		for(int j = 0;j <=11;j++)
 			cout<<p[i][j]<<" ";
 		cout<<endl;
 	}
 	bool T = true;
 	int dr,dc; 
 	int tr,tc; 
 	int length = 0;
 	while(T){
 		Position tmp = Q.front();
 		Q.pop();
 		for(int i = 0;i < 4;i++){
 			 dr = tmp.r+ dir[i][0];
 			 dc = tmp.c+ dir[i][1];
 			if(dr == finish.r && dc == finish.c){
 				p[dr][dc] = p[tmp.r][tmp.c]+1;
 				length = p[tmp.r][tmp.c]-1;
 				cout<<"¾­¹ý"<<length<<"¸öµã"<<endl;
 				T = false; 
 				break;
			 }
 			else if(p[dr][dc] == 0){
 				p[dr][dc] = p[tmp.r][tmp.c]+1;
 				Position N(dr,dc);
				Q.push(N); 
 			}
 				
		 }
		 if(Q.empty())
		 	return false; 
		
	 }	for(int i = 0; i <= 7;i++){
 				for(int j = 0;j <=8;j++)
 				cout<<p[i][j]<<" ";
 				cout<<endl;
 			}
 			cout<<endl<<endl;
	int **path;
	path = new int*[length+1];
	for(int i = 0;i <= length;i++)
		path[i] = new int[2];
	int t = length; 
	bool PID = true;
	
	while(PID){
		PID = false;
		for(int i = 0;i < 4;i++){
			tr = dr + dir[i][0];
			tc = dc + dir[i][1];
			if(p[tr][tc] == p[dr][dc] - 1){
				dr = tr,dc = tc;
				
				path[t][0] = tr;
				path[t][1] = tc;
				t--;
				PID = true;
				break;	                                                                                  
			} 
		} 
		if(!t)
			break;
	} 

	for(int i = 1;i <= length;i++)
		cout<<path[i][0]<<" "<<path[i][1]<<endl;
	return true; 
 }
 int main(){
 	int pt[maxn][maxn];
 	memset(pt,0,sizeof pt);
 	
 	int n = 20,m = 30,t;
 	for(int i = 0; i <= n+1;i++)
 		pt[i][0] = pt[i][m+1] = 1;
	for(int i = 0;i <= m+1;i++)
	 	pt[0][i] = pt[n+1][i] = 1;
	int point[14][2] = {1,3,2,3,2,4,3,5,4,4,4,5,5,1,5,5,6,1,6,2,6,3,7,1,7,2,7,3};
	for(int i = 0;i < 13;i++){
		int u = point[i][0];
		int v = point[i][1];
		pt[u][v] = 1;
	}                                                                                                      
	/*
	cin>>t;
	for(int i = 0; i < t;i++){
		int u,v;
		cin>>u>>v;
		pt[u][v] = 1;
	}
	*/
	Position s(3,2);
	Position f(4,6);
	FindPath(s,f,pt);
 	
 }