Skip to content

1765. Map of Highest Peak 👍

  • Time: $O(mn)$
  • Space: $O(mn)$
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
class Solution {
 public:
  vector<vector<int>> highestPeak(vector<vector<int>>& isWater) {
    constexpr int dirs[4][2] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
    const int m = isWater.size();
    const int n = isWater[0].size();
    vector<vector<int>> ans(m, vector<int>(n, -1));
    queue<pair<int, int>> q;

    for (int i = 0; i < m; ++i)
      for (int j = 0; j < n; ++j)
        if (isWater[i][j] == 1) {
          q.emplace(i, j);
          ans[i][j] = 0;
        }

    while (!q.empty()) {
      const auto [i, j] = q.front();
      q.pop();
      for (const auto& [dx, dy] : dirs) {
        const int x = i + dx;
        const int y = j + dy;
        if (x < 0 || x == m || y < 0 || y == n)
          continue;
        if (ans[x][y] != -1)
          continue;
        ans[x][y] = ans[i][j] + 1;
        q.emplace(x, y);
      }
    }

    return ans;
  }
};

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
class Solution {
  public int[][] highestPeak(int[][] isWater) {
    final int[][] dirs = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
    final int m = isWater.length;
    final int n = isWater[0].length;
    int[][] ans = new int[m][n];
    Arrays.stream(ans).forEach(A -> Arrays.fill(A, -1));
    Queue<Pair<Integer, Integer>> q = new ArrayDeque<>();

    for (int i = 0; i < m; ++i)
      for (int j = 0; j < n; ++j)
        if (isWater[i][j] == 1) {
          q.offer(new Pair<>(i, j));
          ans[i][j] = 0;
        }

    while (!q.isEmpty()) {
      final int i = q.peek().getKey();
      final int j = q.poll().getValue();
      for (int[] dir : dirs) {
        final int x = i + dir[0];
        final int y = j + dir[1];
        if (x < 0 || x == m || y < 0 || y == n)
          continue;
        if (ans[x][y] != -1)
          continue;
        ans[x][y] = ans[i][j] + 1;
        q.offer(new Pair<>(x, y));
      }
    }

    return ans;
  }
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
class Solution:
  def highestPeak(self, isWater: list[list[int]]) -> list[list[int]]:
    dirs = ((0, 1), (1, 0), (0, -1), (-1, 0))
    m = len(isWater)
    n = len(isWater[0])
    ans = [[-1] * n for _ in range(m)]
    q = collections.deque()

    for i in range(m):
      for j in range(n):
        if isWater[i][j] == 1:
          q.append((i, j))
          ans[i][j] = 0

    while q:
      i, j = q.popleft()
      for dx, dy in dirs:
        x = i + dx
        y = j + dy
        if x < 0 or x == m or y < 0 or y == n:
          continue
        if ans[x][y] != -1:
          continue
        ans[x][y] = ans[i][j] + 1
        q.append((x, y))

    return ans