Coast Length

#include<iostream>
#include<algorithm>

using namespace std;

int board[1001][1001];

void getBoard(int n, int m)
{
    char c = getchar();
    for (int i=0;i<n;i++)
    {
        c = getchar();
        for (int j=0; j<m;j++)
        {
            if (c=='1')
                board[i][j]=1;
            else board[i][j]=0;
            c = getchar();
        }
    }
}

void findSea(int n, int m, int &x, int &y)
{
    for (int i=0;i<m;i++)
    {
        if (board[0][i]==0)
        {
            x=0; y=i;
            return;
        }
        if (board[n-1][i]==0)
        {
            x=n-1; y=i;
            return;
        }
    }
    for (int i=0;i<n;i++)
    {
        if (board[i][0]==0)
        {
            x=i; y=0;
            return;
        }
        if (board[i][m-1]==0)
        {
            x=i; y=m-1;
            return;
        }
    }
    x=-1; y=-1;
}

typedef struct pos
{
    int x,y;
}pos;

void BFS(int n, int m, int x, int y)
{
    pos *queue = new pos[1000000];
    queue[0].x=x; queue[0].y=y;
    board[x][y]=2;
    int start=0, end=1;
    while (start < end)
    {
        int x1 = queue[start].x, y1= queue[start].y;
        if (x1-1>=0 && board[x1-1][y1]==0)
        {
            queue[end].x=x1-1;
            queue[end].y=y1;
            end++;
            board[x1-1][y1]=2;
        }
        if (x1+1<n && board[x1+1][y1]==0)
        {
            queue[end].x=x1+1;
            queue[end].y=y1;
            end++;
            board[x1+1][y1]=2;
        }
        if (y1-1>=0 && board[x1][y1-1]==0)
        {
            queue[end].x=x1;
            queue[end].y=y1-1;
            end++;
            board[x1][y1-1]=2;
        }
        if (y1+1<m && board[x1][y1+1]==0)
        {
            queue[end].x=x1;
            queue[end].y=y1+1;
            end++;
            board[x1][y1+1]=2;
        }
        start++;
    }
}

int find(int n, int m)
{
    int count=0;
    for (int i=0;i<n;i++)
        for (int j=0; j<m;j++)
        {
            if (board[i][j]==2)
            {
                int x, y, c2=0;
                x=i-1; y=j;
                if (x>=0 && board[x][y]==1)
                {
                    c2++;
                }
                x=i+1; y=j;
                if (x<n && board[x][y]==1)
                {
                    c2++;
                }
                x=i; y=j-1;
                if (y>=0 && board[x][y]==1)
                {
                    c2++;
                }
                x=i; y=j+1;
                if (y<m && board[x][y]==1)
                {
                    c2++;
                }
                count += c2;
            }
        }
    for (int i=0;i<m;i++)
    {
        if (board[0][i]==1)
            count++;
        if (board[n-1][i]==1)
            count++;
    }
    for (int i=0;i<n;i++)
    {
        if (board[i][0]==1)
            count++;
        if (board[i][m-1]==1)
            count++;
    }
    return count;
}

int main()
{
    int n,m;
    cin >> n >> m;
    getBoard(n, m);
    int x,y;
    findSea(n,m,x,y);
    while (x!=-1 && y!=-1)
    {
        BFS(n,m,x,y);
        findSea(n,m,x,y);
    }
    cout << find(n, m);
    return 0;
}