hdu 1175 连连看 java (BFS + 一搜到底)

 

import java.io.*;import java.util.*;class Node{int x, y, pre, num;Node(int x, int y, int pre, int num){this.x = x;this.y = y;this.pre = pre;this.num = num;}}public class Main1175{static int dir[][] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};static boolean hash[][] = new boolean[1005][1005];static int map[][] = new int[1005][1005];static int x1, y1, x2, y2;static int n, m;static PrintWriter cout = new PrintWriter (new OutputStreamWriter(System.out));static boolean index(Node now){if(now.x >= 0 && now.x < n && now.y >= 0 && now.y < m && now.num <= 2 && map[now.x][now.y] == 0)return true;return false;}static void BFS(){if(map[x1][y1] != map[x2][y2] || map[x1][y1] == 0 || map[x2][y2] == 0){cout.println("NO");return ;}for(int i = 0; i <= n; i++)for(int j = 0; j <= m; j++)hash[i][j] = false;int tx, ty, tpre, tnum;int mx, my;Queue<Node> Q = new LinkedList<Node>();for(int i = 0; i < 4; i++){tx = x1 + dir[i][0];ty = y1 + dir[i][1];tpre = i;tnum = 0;Node next = new Node(tx, ty, tpre, tnum);hash[x1][y1] = true;if(tx == x2 && ty == y2 && tnum <= 2 ){cout.println("YES");cout.flush();return ;}if(!index(next))continue;if(!hash[next.x][next.y] ){Q.add(next);hash[next.x][next.y] = true;}mx = next.x;my = next.y;while(true){tx = mx + dir[i][0];ty = my + dir[i][1];tpre = i;tnum = 0;if(tx == x2 && ty == y2 && tnum <= 2 ){cout.println("YES");cout.flush();return ;}Node mid = new Node(tx, ty, tpre, tnum);if(index(mid)){if(!hash[mid.x][mid.y]){Q.add(mid);hash[mid.x][mid.y] = true;}}elsebreak;mx = mid.x;my = mid.y;}}Node now = new Node(0, 0, 0, 0);while(!Q.isEmpty()){now = Q.poll();if(now.x == x2 && now.y == y2 ){cout.println("YES");return ;}if (now.num >= 2) {continue;}mx = now.x;my = now.y;tpre = now.pre;tnum = now.num;while(true){tx = mx + dir[tpre][0];ty = my + dir[tpre][1];if(tx == x2 && ty == y2 && tnum <= 2){cout.println("YES");return ;}Node mid = new Node(tx, ty, tpre, tnum);if(index(mid)){if(!hash[mid.x][mid.y]){Q.add(mid);hash[mid.x][mid.y] = true;}}elsebreak;mx = mid.x;my = mid.y;}for(int i = 0; i < 4; i++){if(i == now.pre)continue;tx = now.x + dir[i][0];ty = now.y + dir[i][1];tpre = i;tnum = now.num + 1;if(tx == x2 && ty == y2 && tnum <= 2 ){cout.println("YES");return ;}Node next = new Node(tx, ty, tpre, tnum);if(!index(next))continue;if(!hash[next.x][next.y]){Q.add(next);hash[next.x][next.y] = true;}mx = next.x;my = next.y;tpre = next.pre;tnum = next.num;while(true){tx = mx + dir[i][0];ty = my + dir[i][1];Node mid = new Node(tx, ty, tpre, tnum);if(tx == x2 && ty == y2 && tnum <= 2 ){cout.println("YES");return ;}if(index(mid)){if(!hash[mid.x][mid.y]){Q.add(mid);hash[mid.x][mid.y] = true;}}elsebreak;mx = mid.x;my = mid.y;}}}cout.println("NO");return ;}public static void main(String[] args) throws IOException{//Scanner cin = new Scanner(System.in);StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));//while(cin.hasNext())while(in.nextToken() != StreamTokenizer.TT_EOF){//n = cin.nextInt();n = (int)in.nval;//m = cin.nextInt();in.nextToken();m = (int)in.nval;if(n == 0 && m == 0)break;for(int i = 0 ;i < n; i++)for(int j = 0; j < m; j++){//map[i][j] = cin.nextInt();in.nextToken();map[i][j] = (int)in.nval;}int t;//t = cin.nextInt();in.nextToken();t = (int)in.nval;while(t-- > 0){//x1 = cin.nextInt();in.nextToken();x1 = (int)in.nval;x1--;//y1 = cin.nextInt();in.nextToken();y1 = (int)in.nval;y1--;//x2 = cin.nextInt();in.nextToken();x2 = (int)in.nval;x2--;//y2 = cin.nextInt();in.nextToken();y2 = (int)in.nval;y2--;BFS();}}cout.flush();}}