题目描述：
假设以一个n*m的矩阵作为棋盘，每个棋位对应一个二维坐标 (x, y)。你有一颗棋子位于左上起点(0, 0)，现在需要将其移动到右下底角 (n-1, m-1)，棋子可以向相邻的上下左右位置移动，每个坐标最多只能经过一次。棋盘中散布着若干障碍，障碍物不能跨越，只能绕行，问是否存在到达右下底角的路线？若存在路线，输出所需的最少移动次数；若不存在，输出0。 Input 第一行三个正整数n，m和k，代表棋盘大小与障碍物个数  1< n、m < 100,  k < n*m 第二行至第k+1行，每行为两个整数x和y，代表k个障碍物的坐标。输入
输入三个正整数n，m和k，代表棋盘大小与障碍物个数  1< n、m < 100,  k < n*m
第二行至第k+1行，每行为两个整数x和y，代表k个障碍物的坐标。输出
输出从起点到终点的最短路径的长度，如果不存在，即输出0

import java.util.Arrays;
import java.util.Scanner;public class Main {public static int min = Integer.MAX_VALUE;public static boolean find = false;public static void main( String[] args ) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();int m = sc.nextInt();int k = sc.nextInt();//障碍boolean[][] go = new boolean[n][m];//棋盘boolean[][] visit = new boolean[n][m];//走过的痕迹//将所有的位置设置为truefor(int i=0;i<n;i++) {Arrays.fill(go[i], true);}//有棋子障碍处设置为falsefor(int i=0;i<k;i++) {int a = sc.nextInt();int b = sc.nextInt();go[a][b] = false;}findPath(0, 0, 0, visit, go, n - 1, m - 1);//如果找到了输出结果，没路输出0if(find) {System.out.println(min);}else {System.out.println(0);}}private static void findPath( int row , int col , int s, boolean[][] visit, boolean[][] go, int targetRow, int targetCol ) {if(row == targetRow && col == targetCol) {//到达目标位置find = true;if(s < min) {min = s;}return;}if(col < targetCol && !visit[row][col+1] && go[row][col+1]) { // 右visit[row][col+1] = true;findPath(row, col + 1, s + 1, visit, go, targetRow, targetCol);visit[row][col+1] = false;}if(row < targetRow && !visit[row+1][col] && go[row+1][col]) { // 下visit[row+1][col] = true;findPath(row + 1, col, s + 1, visit, go, targetRow, targetCol);visit[row+1][col] = false;}if(col > 0 && !visit[row][col-1] && go[row][col-1]) { // 左visit[row][col-1] = true;findPath(row, col - 1, s + 1, visit, go, targetRow, targetCol);visit[row][col-1] = false;}if(row > 0 && !visit[row-1][col] && go[row-1][col]) { // 上visit[row-1][col] = true;findPath(row - 1, col, s + 1, visit, go, targetRow, targetCol);visit[row-1][col] = false;}}
}

import java.util.Scanner;
import java.util.Stack;public class Main{public static void main(String[] args) {Scanner sc = new Scanner(System.in);String str = sc.nextLine();String results = getRealContent(str);System.out.println(results);}public static String getRealContent(String str) {StringBuilder sb = new StringBuilder("");char flag = '(';Stack<Character> stack = new Stack<Character>();char[] chars = str.toCharArray();//遍历每个数组将其放入栈中for (int i = 0; i < chars.length; i++) {if (chars[i] =='(') {//入栈
                stack.push(chars[i]);}else if (chars[i] ==')') {//弹出和这个)对应的(以及他们中间的内容while(!stack.isEmpty() && stack.peek()!= flag){stack.pop();}stack.pop();}else if (chars[i] =='<') {//删除前面的一个内容if(!stack.empty() && stack.peek()!=flag){stack.pop();}}else{stack.push(chars[i]);}}while(!stack.empty()){sb.append(stack.pop());}return sb.reverse().toString();}
}

import java.util.Scanner;public class Main {public static void main( String[] args ) {Scanner sc = new Scanner(System.in);String s = sc.next();String res = "";int count = 0, len = s.length();for(int i=0;i<len;i++) {char c = s.charAt(i);if(c == '(') {count ++;}else if(c == ')') {count --;}else if(c == '<') {if(res.length() > 0 && count == 0 && res.charAt(res.length() - 1) != ')') {res = res.substring(0, res.length() - 1);}}else if(count == 0) {res += c;}}System.out.println(res);}
}

import java.util.*;
/*** 5* .#...* ..#S.* .E###* .....* .....*/
public class B {static int[][] d = {{-1, 0},{0, 1},{1, 0},{0, -1}};static int startX = 0;static int startY = 0;static int endX = 0;static int endY = 0;static Set<Integer> stepList = new HashSet<>();public static void main(String[] args) {Scanner in = new Scanner(System.in);int n = in.nextInt();in.nextLine();char[][] board = new char[n][n];for (int i = 0; i < n; i++) {String line = in.nextLine();for (int j = 0; j < n; j++) {board[i][j] = line.charAt(j);if (board[i][j] == 'S') {startX = i;startY = j;} else if (board[i][j] == 'E') {endX = i;endY = j;}}}shortestLength(board, n);if (stepList.size() == 0) {System.out.println(-1);return;}int minStep = Integer.MAX_VALUE;for (Integer integer : stepList) {if (integer < minStep) {minStep = integer;}}System.out.println(minStep);}private static void shortestLength(char[][] board, int n) {boolean[][] visited = new boolean[n][n];visited[startX][startY] = true;shortestLength(board, n, startX, startY, 0, visited);}private static void shortestLength(char[][] board, int n, int startX, int startY, int step, boolean[][] visited) {if (startX == endX && startY == endY) {stepList.add(step);return;}for (int i = 0; i < 4; i++) {int newX = startX + d[i][0];int newY = startY + d[i][1];if (newX < 0) {newX = n - 1;} else if (newX==n) {newX = 0;}if (newY <0) {newY = n-1;}else if (newY==n){newY = 0;}if (board[newX][newY] !='#' && !visited[newX][newY]) {visited[newX][newY] = true;shortestLength(board, n, newX, newY, step + 1, visited);visited[newX][newY] = false;}}}}