求迷宫出路以及最优解，小试牛刀。

迷宫求出路是件很简单的事情，相信大家一定能够掌握。
有两种方法：1.回溯法 2.递归法

【回溯法】：用栈来保存所走过的路径，将他们入栈，等到无路（四个方向都走完了）那就退回到上一步中，再次进行试探。
注意：每走过一个路径时，对它进行标记，方便我们进行探测。

这里：我们把回溯过的路径记为3，走过但没回溯的路径标记为2
提醒大家：先看主函数，建立框架在进行细节上的突破。

//完成迷宫#pragma warning (disable:4996)#include<iostream>#include<vector>#include<stack>using namespace std;#include<assert.h>//创建迷宫->动态创建二维数组：1.int[][N]  2.int*->（二维数组是按照一维数组来存储的）//打印迷宫//走迷宫const size_t N = 10;//定义全局变量Nstruct Pos{    int _row;    int _col;};//思考：三元组->适合适合什么问题？迷宫？二维数组？void InitMaze(int maze[][N]){    FILE*fout = fopen("MazeMap.txt", "r");    assert(fout);    for (int i = 0; i < N; ++i)    {        for (int j = 0; j < N;)        {            //获取文件中的字符用fgetc()            char ch = fgetc(fout);            if (ch == '0' || ch == '1')//因为在文件中保存，所有数字均为字符数字            {                maze[i][j] = ch-'0';                ++j;            }        }    }}void PrintMaze(int maze[][N]){    for (int i = 0; i < N; ++i)    {        for (int j = 0; j < N; ++j)        {            cout << maze[i][j] << " ";        }        cout << endl;    }    cout << endl;}bool CheckAccess(int maze[][N], Pos tmp){    if (tmp._row >= 0 && tmp._row < N        &&tmp._col >= 0 && tmp._col < N        &&maze[tmp._row][tmp._col] == 0)    {        return true;    }    return false;}//获取迷宫路径void GetMazePath(int maze[][N], Pos entry){    //回溯法->将路径压入栈    //试探法，对每个方向进行试探一下    stack<Pos>path;    path.push(entry);    while (!path.empty())    {        Pos cur = path.top();        Pos next = cur;        if (cur._row == N - 1)        {            break;        }        //试探法，对每个方向进行试探一下        //上方          next._row--;        if (CheckAccess(maze,next))        {            maze[next._row][next._col] = 2;            path.push(next);            continue;        }        next = cur;        //右方        next._col++;        if (CheckAccess(maze, next))        {            maze[next._row][next._col] = 2;            path.push(next);            continue;        }        next = cur;        //下方          next._row++;        if (CheckAccess(maze, next))        {            maze[next._row][next._col] = 2;            path.push(next);            continue;        }        next = cur;        //右方        next._col--;        if (CheckAccess(maze, next))        {            maze[next._row][next._col] = 2;            path.push(next);            continue;        }        //四个方向都走不通-》回溯法        maze[cur._row][cur._col] = 3;        path.pop();    }}int main(){    int maze[N][N];    InitMaze(maze);    PrintMaze(maze);    Pos entry = { 1.1 };    GetMazePath(maze, entry);    PrintMaze(maze);    return 0;}

【递归法】求迷宫最优解（即最短路径）

bool GetMazePathR(int maze[][N], size_t n, Pos cur,                  stack<Pos>& shortPath, stack<Pos>& path){    path.push(cur);    if (cur._row == n-1)    {        if (shortPath.empty() || path.size() < shortPath.size())        {            shortPath = path;        }        //return true;    }    //maze[cur._row][cur._col] = 2;    Pos next;    // 上    next = cur;    next._row -= 1;    if (CheckAccess(maze, n, cur, next))    {        maze[next._row][next._col] = maze[cur._row][cur._col]+1;        if(GetMazePathR(maze, n, next, shortPath, path))            return true;    }    // 右    next = cur;    next._col += 1;    if (CheckAccess(maze, n, cur, next))    {        maze[next._row][next._col] = maze[cur._row][cur._col]+1;        //if (GetMazePathR(maze, n, next))        if(GetMazePathR(maze, n, next, shortPath, path))            return true;    }    // 下    next = cur;    next._row += 1;    if (CheckAccess(maze, n, cur, next))    {        maze[next._row][next._col] = maze[cur._row][cur._col]+1;        //if (GetMazePathR(maze, n, next))        if(GetMazePathR(maze, n, next, shortPath, path))            return true;    }    // 左    next = cur;    next._col -= 1;    if (CheckAccess(maze, n, cur, next))    {        maze[next._row][next._col] = maze[cur._row][cur._col]+1;        //if (GetMazePathR(maze, n, next))        if(GetMazePathR(maze, n, next, shortPath, path))            return true;    }    path.pop();    return false;}int main(){    int maze[N][N];    InitMaze(maze);    PrintMaze(maze);    Pos entry = { 1,0 };    //GetMazePath(maze, entry);    //PrintMaze(maze);    stack<Pos>path;    stack<Pos>shortPath;    GetMazePathR(maze,N,entry,shortPath,path );    PrintMaze(maze);    return 0;}