遞歸~紅與黑

輸出個數：

#include<iostream>
#include<string>
using namespace std;
const size_t row = 21, column = 21;
char str[row][column];
int w, h;


int f(int x, int y)
{
    if(x < 0 || y < 0 || x >= h || y >= w)        //超區矩陣範圍
        return 0;
    if(str[x][y] == '#')
        return 0;
    else
    {
        str[x][y] = '#';        //標記走過的磚
        return f(x, y-1) + f(x, y+1) + f(x-1,y) + f(x+1,y) + 1;
    }
}
int main()
{
    cout << "Enter the row and the column: " << endl;
    cin >> w >> h;
    cout << "Enter the stings: " << endl;
    for(size_t ix = 0; ix != h; ++ix)
    for(size_t index = 0; index != w; ++index)
        cin >> str[ix][index];
    for(size_t ix = 0; ix != h; ++ix)
        for(size_t index = 0; index != w; ++index)
            if(str[ix][index] == '@')
                cout << f(ix,index) << endl;
    return 0;
}

結果：45

輸出走過的路徑(不重複)：

#include<iostream>
#include<string>
#include<cstring>
#include<cstdlib>
using namespace std;
const size_t row = 21, column = 21;
char str[row][column];
int a[row][column];
int w, h;
int f(int x, int y)
{
    int m, n, flag = 1;
    char str1[200] = {}, str2[200] = {}, str3[500] = {};
    if(x < 0 || y < 0 || x >= h || y >= w)
        return 0;
    if(str[x][y] == '#')
        return 0;
    else
    {
        itoa(x, str1, 10);
        itoa(y, str2, 10);
        strcat(str3, "(");
        strcat(str3, str1);
        strcat(str3, "!");
        strcat(str3, str2);
        strcat(str3, ")\t");
        if(a[x][y] == 0)
            cout << str3;
        a[x][y] =1;
        if(f(x-1,y) != 0 && f(x, y+1) != 0 && flag)
        {
            m = x;
            n = y;
            flag = 0;
        }
        str[x][y] = '#';
        if(f(x-1, y) != 0)
            f(x-1,y);
        else if(f(x, y+1) != 0)
            f(x, y+1);
        else if(f(x+1, y) != 0)
            f(x+1, y);
        else if(f(x, y-1) != 0)
            f(x, y-1);
        else
            f(m, n-1);
    }
}
int main()
{
    cout << "Enter the wideth and the hight: " << endl;
    cin >> w >> h;
    for(size_t ix = 0; ix != h; ++ix)
        for(size_t index = 0; index != w; ++index)
        {
            cin >> str[ix][index];
            if(str[ix][index] == '#')
                a[ix][index] = 1;
        }
    for(size_t ix = 0; ix != h; ++ix)
        for(size_t index = 0; index != w; ++index)
            if(str[ix][index] == '@')
            {
                f(ix, index);
                break;
            }
    cout << endl;
    return 0;
}

//輸出走過的路徑（重複）：

#include<iostream>
#include<string>
#include<cstring>
#include<cstdlib>
using namespace std;
const size_t row = 21, column = 21;
char str[row][column];
//int a[row][column];
int w, h;
int f(int x, int y)
{
    int m, n, flag = 1;
    char str1[200] = {}, str2[200] = {}, str3[500] = {};
    if(x < 0 || y < 0 || x >= h || y >= w)
        return 0;
    if(str[x][y] == '#')
        return 0;
    else
    {
        itoa(x, str1, 10);
        itoa(y, str2, 10);
        strcat(str3, "(");
        strcat(str3, str1);
        strcat(str3, "!");
        strcat(str3, str2);
        strcat(str3, ")\t");
        //if(a[x][y] == 0)
            cout << str3;
        //a[x][y] =1;
        if(f(x-1,y) != 0 && f(x, y+1) != 0 && flag)
        {
            m = x;
            n = y;
            flag = 0;
        }
        str[x][y] = '#';
        if(f(x-1, y) != 0)
            f(x-1,y);
        else if(f(x, y+1) != 0)
            f(x, y+1);
        else if(f(x+1, y) != 0)
            f(x+1, y);
        else if(f(x, y-1) != 0)
            f(x, y-1);
        else
            f(m, n-1);
    }
}
int main()
{
    cout << "Enter the wideth and the hight: " << endl;
    cin >> w >> h;
    for(size_t ix = 0; ix != h; ++ix)
        for(size_t index = 0; index != w; ++index)
        {
            cin >> str[ix][index];
            //if(str[ix][index] == '#')
               // a[ix][index] = 1;
        }
    for(size_t ix = 0; ix != h; ++ix)
        for(size_t index = 0; index != w; ++index)
            if(str[ix][index] == '@')
            {
                f(ix, index);
                break;
            }
    cout << endl;
    return 0;
}

同時歡迎提出寶貴意見，以幫助我改進，不勝感激！！！

——桑海整理