Solution.cpp

class Solution {
public:
    const int dirs[5] = {-1, 0, 1, 0, -1};

    vector<vector<int>> highestPeak(vector<vector<int>>& isWater) {
        int m = isWater.size(), n = isWater[0].size();
        vector<vector<int>> ans(m, vector<int>(n));
        queue<pair<int, int>> q;
        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.emplace(i, j);
                }
            }
        }
        while (!q.empty()) {
            auto [i, j] = q.front();
            q.pop();
            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.emplace(x, y);
                }
            }
        }
        return ans;
    }
};