C :

#include<stdio.h>
#include<string.h>
struct Node
{
    int X, Y;
};
int main( int argc, char **argv )
{
    int N, StartX, StartY;
    while( scanf( "%d%d%d", &N, &StartX, &StartY ) != EOF )
    {
        struct Node Queue[1000];
        int Head, Tail;
        int Map[31][31], Book[31][31] = { 0 };
        int i, j, k, Sum, TmpX, TmpY;
        int Next[4][2] = { { 0, 1 }, { 1, 0 }, { 0, -1 }, { -1, 0 } };
		for( i = 1; i <= N; ++i )
			for( j = 1; j <= N; ++j )
				scanf( "%d", &Map[i][j]);
		Head = 0, Tail =0;
		Queue[Tail].X = StartX, Queue[Tail].Y = StartY;
		Tail++;
		Book[StartX][StartY] = 1;
		Sum = 1;
		while( Head < Tail )
		{
			for( k = 0; k < 4; ++k )
			{
				TmpX = Queue[Head].X + Next[k][0], TmpY = Queue[Head].Y + Next[k][1];
				if( TmpX < 1 || TmpX > N || TmpY < 1 || TmpY > N )
					continue;
				if( Map[TmpX][TmpY] > 0 && Book[TmpX][TmpY] == 0 )
				{
					Sum++;
					Book[TmpX][TmpY] = 1;
					Queue[Tail].X = TmpX, Queue[Tail].Y = TmpY;
					Tail++;
				}
			}
			Head++;
		}
		printf( "%d\n", Sum );
    }
    return 0;
}

C++ :

#include <stdio.h>
#include <iostream>
using namespace std;

struct note
{
	int x;
	int y;
};

int main()
{
	// 满足4连通的海域点
	int next[4][2] = { { 0, 1 },  // 右
	{ 1, 0 },  // 下
	{ 0, -1 }, // 左
	{ -1, 0 }   // 上
	};
	int n, startx, starty;

	// 海域尺寸n以及降落点的坐标(startx,starty)
	while (cin >> n >> startx >> starty)
	{
		struct note que[901];
		int head, tail;
		int a[31][31];
		int book[31][31] = { 0 };
		int i, j, k, sum, max = 0, targetx, targety;

		for (i = 1; i <= n; i++)
		for (j = 1; j <= n; j++)
			cin >> a[i][j];

		head = 1;
		tail = 1;
		que[tail].x = startx; // 往队列插入降落的起始坐标
		que[tail].y = starty;
		tail++;
		book[startx][starty] = 1;      // 陆地点标记
		sum = 1;      // 陆地面积


		while (head<tail)
		{
			for (k = 0; k <= 3; k++) // 逐一判断满足4连通的海域点：是否为陆地或者曾经遍历
			{
				targetx = que[head].x + next[k][0];
				targety = que[head].y + next[k][1];

				if (targetx<1 || targetx>n || targety<1 || targety>n)
					continue;

				if (a[targetx][targety]>0 && book[targetx][targety] == 0)
				{
					sum++;
					book[targetx][targety] = 1;
					que[tail].x = targetx;
					que[tail].y = targety;
					tail++;
				}
			}

			head++;
		}

		cout << sum << endl;
	}
	return 0;
}

Java :

import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while(in.hasNext()){
			int n =in.nextInt();
			int a =in.nextInt();
			int b =in.nextInt();
			int[][] map = new int[n][n];
			boolean[][] visited = new boolean[n][n];
			for(int i=0;i<visited.length;i++){
				for(int k=0;k<visited[0].length;k++)
					visited[i][k] =false;
			}
			for(int i=0;i<map.length;i++){
				for(int k=0;k<map[0].length;k++)
					map[i][k] =in.nextInt();
			}
			int count =find(map,visited,a-1,b-1);
			System.out.println(count);
		}
	}

	private static int find(int[][] map, boolean[][] visited, int i, int j) {
		// TODO Auto-generated method stub
		if(i<0||i>=map.length||j<0||j>=map[0].length||visited[i][j]==true||map[i][j]==0)
			return 0;
		else{
			visited[i][j] = true;
			return 1+find(map,visited,i-1,j)+
						find(map,visited,i+1,j)+
							find(map,visited,i,j+1)+
								find(map,visited,i,j-1);
		}
		
	}
}