Training #2 cell battle (BFS)

Constraints:

1 <= R, C <= 500

1 <= T <= 5

Sample Input:

5

3 5

#####

a...b

#####

3 4

####

a..b

####

3 3

#c#

a.b

#d#

3 3

#c#

...

a.b

3 5

.....

.#.#.

a...b

Sample Output:

#####

aa*bb

#####

####

aabb

####

#c#

a*b

#d#

#c#

acb

a*b

aa*bb

a#.#b

aa*bb

#include <bits/stdc++.h>
#include <cstring>
#include <iostream>
#include <algorithm>
#define foror(i,a,b) for(i=a;i<b;i++)
#define foror2(i,a,b) for(i=a;i>b;i--)
#define EPS 1e-9
#define PI acos(-1.0)
#define INF 1000000000
#define MOD 1000000007
#define mem(a,b) memset((a),b,sizeof(a))
#define TS printf("!!!
")
#define lson o<<1, l, m
#define rson o<<1|1, m+1, r
using ll = long long;
using ull= unsigned long long;
//std::ios::sync_with_stdio(false);
using namespace std;
char s[505][505];
int visit[505][505];
int dx[4]={-1,0,0,1};
int dy[4]={0,-1,1,0};
int a,b;
int sum;
struct point{
 int x,y;
 char ch;
 int num;
};
queue<point> q;
bool check(point jqk)
{
 if((jqk.x>=1&&jqk.x<=a)&&(jqk.y>=1&&jqk.y<=b)&&(s[jqk.x][jqk.y]!='#')&&(s[jqk.x][jqk.y]!='*'))
 return true;
 return false;
}
char readchar()
{
    char tmp = 0;
    char ch;
    bool read = false;
    while (ch = getchar())
    {
        if ((ch >='a'&&ch<='z')||ch=='#'||ch=='.')
        {
            read = true;
            tmp = ch;
        }
        else if (read)
        {
            break;
        }
        else
        {
            continue;
        }
    }
    return tmp;
}
void bfs()
{
 while(!q.empty())
 {
  point aim=q.front();
  q.pop();
  //cout << aim.ch << " ";
  if(s[aim.x][aim.y]!='*')
  for(int i=0;i<=3;i++)
  {
        point cur;
        cur.x=aim.x+dx[i];
        cur.y=aim.y+dy[i];
        cur.ch=aim.ch;
        cur.num=aim.num+1;
        if(check(cur))
        {
        if(s[cur.x][cur.y]>='a'&&s[cur.x][cur.y]<='z')
        {
        if(s[cur.x][cur.y]==cur.ch)
        continue;
        else
        {
        if(visit[cur.x][cur.y]!=cur.num)
        continue;
        else
        {
        s[cur.x][cur.y]='*';
        }
        }
        }
        else if(s[cur.x][cur.y]=='.')
        {
        s[cur.x][cur.y]=cur.ch;
        visit[cur.x][cur.y]=cur.num;
        q.push(cur);
        }
        }
  }
 }
}
int main()
{
 //freopen("in.txt", "r", stdin);
 //freopen("out.txt", "w", stdout);
 int T;
 cin >>T;
 while(T--)
 {
         mem(visit,0);
         char pop;
         scanf("%d %d",&a,&b);
         point aim;
         for(int i=1;i<=a;i++)
                scanf("%s",s[i]+1);
         /*for(int i=1;i<=a;i++)
                printf("%s
",s[i]+1);*/
         for(int i=1;i<=a;i++)
                for(int j=1;j<=b;j++)
         {
                pop=s[i][j];
                if(pop!='#'&&pop!='.')
                {
                aim.x=i;
                aim.y=j;
                aim.ch=pop;
                aim.num=1;
                q.push(aim);
                visit[i][j]=1;
                }
         }
         if(!q.empty())
                bfs();
         for(int i=1;i<=a;i++)
                printf("%s
",s[i]+1);
                printf("
");
                printf("
");

 }
 //fclose(stdin);
 //fclose(stdout);
 return 0;
}