输入：

5 5

SOLO

CPUCY

EKLQH

CRSOL

EKLQO

PGRBC

输出：

YES

这道题目比较基础，遍历数组找到开头字母，再BFS或者DFS遍历就可以找到了。但是需要注意一点，就是字母不能重用，比如上面输入“SOLO”输出YES，但输入“SOLOL”则没返回结果，因为'L'重用。

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;public class Main {static boolean result = false;public static void main(String[] args) {Scanner cin = new Scanner(System.in);int n = 0, m = 0;if (cin.hasNext()) {n = cin.nextInt();m = cin.nextInt();}String target = cin.next();char arrs[][] = new char[n][m];int i = 0;while (cin.hasNext()) {String temp = cin.next();for (int j = 0; j < temp.length(); j++) {arrs[i][j] = temp.charAt(j);}i++;if (i == n)break;}char first = target.charAt(0);for (i = 0; i < arrs.length; i++) {for (int j = 0; j < arrs[i].length; j++) {if (arrs[i][j] == first) {HashSet set = new HashSet();find(arrs, n, m, i, j, target, set);if (result)break;}}}}private static void find(char[][] arrs, int n, int m, int i, int j,String target, HashSet hashSet) {// TODO Auto-generated method stubchar first = target.charAt(0);if (arrs[i][j] != first) {return;}if (hashSet.contains(i + j)) {return;}if (target.length() == 1) {System.out.println("YES");result = true;return;}hashSet.add(i + j);target = target.substring(1);for (int len = 0; len < 4; len++) {HashSet temp = new HashSet(hashSet);switch (len) {case 0:if (i > 0)find(arrs, n, m, i - 1, j, target, temp);elsereturn;break;case 1:if (i < n - 1)find(arrs, n, m, i + 1, j, target, temp);elsereturn;break;case 2:if (j > 0)find(arrs, n, m, i, j - 1, target, temp);elsereturn;break;case 3:if (j < m - 1)find(arrs, n, m, i, j + 1, target, temp);elsereturn;break;default:break;}}}
}