BFS。这里用了queue，以及在数据结构里存了上一个的高度。也可以递归调用完成BFS，在调用之前做判断：

import java.util.*;public class TopographicalImage{    public int[] calcPeakAreas(String[] topoData)    {        int m = topoData.length;        int n = topoData[0].length();        ArrayList
     
       ans = new ArrayList
      
       ();        int total = 0;        boolean[][] visited = new boolean[m][n];        while (total < m * n)        {            int max = -1;            Pair p = new Pair(0, 0, 0);            for (int i = 0; i < m; i++)            {                for (int j = 0; j < n; j++)                {                    if (!visited[i][j] && topoData[i].charAt(j) > max)                    {                        max = topoData[i].charAt(j);                        p.x = i;                        p.y = j;						p.lastHeight = max;                    }                }            }            Queue
       
         queue = new LinkedList
        
         ();            queue.add(p);            int cnt = 0;            while (queue.size() != 0)            {                Pair t = queue.poll();				int h = topoData[t.x].charAt(t.y);                if (!visited[t.x][t.y] &&  h <= t.lastHeight)                {                    visited[t.x][t.y] = true;                    cnt++;                    if (t.y + 1 < n) queue.add(new Pair(t.x, t.y + 1, h));                    if (t.x + 1 < m) queue.add(new Pair(t.x + 1, t.y, h));                    if (t.y - 1 >= 0) queue.add(new Pair(t.x, t.y - 1, h));                    if (t.x - 1 >= 0) queue.add(new Pair(t.x - 1, t.y, h));					if (t.x + 1 < m && t.y + 1 < n) queue.add(new Pair(t.x + 1, t.y + 1, h));                    if (t.x + 1 < m && t.y - 1 >= 0) queue.add(new Pair(t.x + 1, t.y - 1, h));                    if (t.x - 1 >= 0 && t.y - 1 >= 0) queue.add(new Pair(t.x - 1, t.y - 1, h));                    if (t.x - 1 >= 0 && t.y + 1 < n) queue.add(new Pair(t.x - 1, t.y + 1, h));                }            }            ans.add(cnt);            total += cnt;        }		int[] res = new int[ans.size()];		for (int i = 0; i < ans.size(); i++)		{			res[i] = ans.get(i);		}		return res;    }} class Pair{    int x;    int y;	int lastHeight;    public Pair(int _x, int _y, int _lastHeight)    {        x = _x;        y = _y;		lastHeight = _lastHeight;    }}