/
994. Rotting Oranges.cpp
64 lines (51 loc) · 1.63 KB
/
994. Rotting Oranges.cpp
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// https://leetcode.com/problems/rotting-oranges/
class Solution
{
int result = 0;
public:
int orangesRotting(vector<vector<int>> &grid)
{
queue<pair<int, int>> cells;
for (int i = 0; i < grid.size(); ++i)
for (int j = 0; j < grid[i].size(); ++j)
if (grid[i][j] == 2)
cells.push({i, j});
BFS(grid, cells);
for (int i = 0; i < grid.size(); ++i)
for (int j = 0; j < grid[i].size(); ++j)
if (grid[i][j] == 1)
return -1;
return result;
}
void BFS(vector<vector<int>> &grid, queue<pair<int, int>> &cells)
{
int directions[] = {-1, 0, 1, 0, -1};
int numCells = cells.size();
while (numCells > 0)
{
while (numCells--)
{
int i = cells.front().first;
int j = cells.front().second;
cells.pop();
for (int k = 0; k < 4; ++k)
{
if (checkBoundaries(grid, i + directions[k], j + directions[k + 1]))
{
grid[i + directions[k]][j + directions[k + 1]] = 2;
cells.push({i + directions[k], j + directions[k + 1]});
}
}
}
numCells = cells.size();
if (numCells > 0)
result++;
}
}
bool checkBoundaries(vector<vector<int>> &grid, int i, int j)
{
if (i < 0 || i >= grid.size() || j < 0 || j >= grid[i].size() || grid[i][j] != 1)
return false;
return true;
}
};