Ultraviolet A 10267-Graphical Editor

Simple simulation + DFS questions. Note that the pixel at Initialization is an uppercase letter 'O' rather than a number '0 '. In addition, ensure that x1 <x2, y1 <y2.

The Code is as follows:

#include <iostream>#include <cstring>#include <cstdlib>#include <cstdio>#include <cmath>using namespace std;int m, n, vis[252][252];char a[252][252], c, cc;void change(int &x, int &y){    if(x > y)    {        int t = x;        x = y;        y = t;    }}void DFS(int x, int y){    if(x < 1 || y < 1 || x > m || y > n || vis[y][x] || a[y][x] != cc)        return ;    a[y][x] = c;    vis[y][x] = 1;    DFS(x + 1, y);    DFS(x - 1, y);    DFS(x, y + 1);    DFS(x, y - 1);}int main(){#ifdef test    freopen("sample.txt", "r", stdin);#endif    int x1, x2, y1, y2;    char name[50], b[3], bb[3];    while(1)    {        scanf("%s", b);        if(b[0] == 'X')            break;        else if(b[0] == 'I')        {            scanf("%d%d", &m, &n);            for(int i = 1; i <= n; i++)                for(int j = 1; j <= m; j++)                    a[i][j] = 'O';        }        else if(b[0] == 'C')            for(int i = 1; i <= n; i++)                for(int j = 1; j <= m; j++)                    a[i][j] = 'O';        else if(b[0] == 'L')        {            scanf("%d%d%s", &x1, &y1, bb);            a[y1][x1] = bb[0];        }        else if(b[0] == 'V')        {            scanf("%d%d%d%s", &x1, &y1, &y2, bb);            change(y1, y2);            for(int i = y1; i <= y2; i++)                a[i][x1] = bb[0];        }        else if(b[0] == 'H')        {            scanf("%d%d%d%s", &x1, &x2, &y1, bb);            change(x1, x2);            for(int i = x1; i <= x2; i++)                a[y1][i] = bb[0];        }        else if(b[0] == 'K')        {            scanf("%d%d%d%d%s", &x1, &y1, &x2, &y2, bb);            change(x1, x2);            change(y1, y2);            for(int i = y1; i <= y2; i++)                for(int j = x1; j <= x2; j++)                    a[i][j] = bb[0];        }        else if(b[0] == 'F')        {            scanf("%d%d%s", &x1, &y1, bb);            c = bb[0];            cc = a[y1][x1];            for(int i = 1; i <= n; i++)                for(int j = 1; j <= m; j++)                    vis[i][j] = 0;            DFS(x1, y1);        }        else if(b[0] == 'S')        {            scanf("%s", name);            puts(name);            for(int i = 1; i <= n; i++)            {                for(int j = 1; j <= m; j++)                    printf("%c", a[i][j]);                printf("\n");            }        }    }    return 0;}