# 542 01 Matrix

### Problem:

Given a matrix consists of 0 and 1, find the distance of the nearest 0 for each cell.

The distance between two adjacent cells is 1. Example 1: Input:

```
0 0 0
0 1 0
0 0 0
```

Output:

```
0 0 0
0 1 0
0 0 0
```

Example 2: Input:

```
0 0 0
0 1 0
1 1 1
```

Output:

```
0 0 0
0 1 0
1 2 1
```

Note:

1. The number of elements of the given matrix will not exceed 10,000.
2. There are at least one 0 in the given matrix.
3. The cells are adjacent in only four directions: up, down, left and right.

### Solutions:

```java
public class Solution {
    public int[][] updateMatrix(int[][] matrix) {
        if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {
            return matrix;
        }
        int[][] dirs = new int[][]{{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
        Queue<Integer> qx = new LinkedList<Integer>();
        Queue<Integer> qy = new LinkedList<Integer>();
        for (int i = 0; i < matrix.length; i ++) {
            for (int j = 0; j < matrix[0].length; j ++) {
                if (matrix[i][j] == 0) {
                    qx.add(i);
                    qy.add(j);
                }
                else {
                    matrix[i][j] = Integer.MAX_VALUE;
                }
            }
        }
        while (!qx.isEmpty()) {
            int x = qx.poll();
            int y = qy.poll();
            for (int i = 0; i < dirs.length; i ++) {
                int nx = x + dirs[i][0];
                int ny = y + dirs[i][1];
                if (nx >= 0 && nx < matrix.length && ny >= 0 && ny < matrix[0].length && matrix[nx][ny] > matrix[x][y] + 1) {
                    matrix[nx][ny] = matrix[x][y] + 1;
                    qx.add(nx);
                    qy.add(ny);
                }
            }
        }
        return matrix;
    }
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://ugopireddy.gitbook.io/leet-code-solutions/solutions-501-550/542-01-matrix.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.