Map of Highest Peak
<p>You are given an integer matrix <code>isWater</code> of size <code>m x n</code> that represents a map of <strong>land</strong> and <strong>water</strong> cells.</p>

<ul>
	<li>If <code>isWater[i][j] == 0</code>, cell <code>(i, j)</code> is a <strong>land</strong> cell.</li>
	<li>If <code>isWater[i][j] == 1</code>, cell <code>(i, j)</code> is a <strong>water</strong> cell.</li>
</ul>

<p>You must assign each cell a height in a way that follows these rules:</p>

<ul>
	<li>The height of each cell must be non-negative.</li>
	<li>If the cell is a <strong>water</strong> cell, its height must be <code>0</code>.</li>
	<li>Any two adjacent cells must have an absolute height difference of <strong>at most</strong> <code>1</code>. A cell is adjacent to another cell if the former is directly north, east, south, or west of the latter (i.e., their sides are touching).</li>
</ul>

<p>Find an assignment of heights such that the maximum height in the matrix is <strong>maximized</strong>.</p>

<p>Return <em>an integer matrix </em><code>height</code><em> of size </em><code>m x n</code><em> where </em><code>height[i][j]</code><em> is cell </em><code>(i, j)</code><em>&#39;s height. If there are multiple solutions, return <strong>any</strong> of them</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<p><strong><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1700-1799/1765.Map%20of%20Highest%20Peak/images/screenshot-2021-01-11-at-82045-am.png" style="width: 220px; height: 219px;" /></strong></p>

<pre>
<strong>Input:</strong> isWater = [[0,1],[0,0]]
<strong>Output:</strong> [[1,0],[2,1]]
<strong>Explanation:</strong> The image shows the assigned heights of each cell.
The blue cell is the water cell, and the green cells are the land cells.
</pre>

<p><strong class="example">Example 2:</strong></p>

<p><strong><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1700-1799/1765.Map%20of%20Highest%20Peak/images/screenshot-2021-01-11-at-82050-am.png" style="width: 300px; height: 296px;" /></strong></p>

<pre>
<strong>Input:</strong> isWater = [[0,0,1],[1,0,0],[0,0,0]]
<strong>Output:</strong> [[1,1,0],[0,1,1],[1,2,2]]
<strong>Explanation:</strong> A height of 2 is the maximum possible height of any assignment.
Any height assignment that has a maximum height of 2 while still meeting the rules will also be accepted.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == isWater.length</code></li>
	<li><code>n == isWater[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 1000</code></li>
	<li><code>isWater[i][j]</code> is <code>0</code> or <code>1</code>.</li>
	<li>There is at least <strong>one</strong> water cell.</li>
</ul>

<p>&nbsp;</p>
<p><strong>Note:</strong> This question is the same as 542: <a href="https://leetcode.com/problems/01-matrix/description/" target="_blank">https://leetcode.com/problems/01-matrix/</a></p>
Breadth-First Search; Array; Matrix
class Solution {
    public int[][] highestPeak(int[][] isWater) {
        int m = isWater.length, n = isWater[0].length;
        int[][] ans = new int[m][n];
        Deque<int[]> q = new ArrayDeque<>();
        for (int i = 0; i < m; ++i) {
            for (int j = 0; j < n; ++j) {
                ans[i][j] = isWater[i][j] - 1;
                if (ans[i][j] == 0) {
                    q.offer(new int[] {i, j});
                }
            }
        }
        int[] dirs = {-1, 0, 1, 0, -1};
        while (!q.isEmpty()) {
            var p = q.poll();
            int i = p[0], j = p[1];
            for (int k = 0; k < 4; ++k) {
                int x = i + dirs[k], y = j + dirs[k + 1];
                if (x >= 0 && x < m && y >= 0 && y < n && ans[x][y] == -1) {
                    ans[x][y] = ans[i][j] + 1;
                    q.offer(new int[] {x, y});
                }
            }
        }
        return ans;
    }
}