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26-rotting-oranges.cpp
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26-rotting-oranges.cpp
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class Solution {
public:
int orangesRotting(vector<vector<int>>& grid)
{
int rows = grid.size();
int cols = grid[0].size();
int oranges = 0, rot = 0, ans = 0;
vector<pair<int, int>> direction = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
queue<pair<int, int>> bfs;
for(int i = 0; i < rows; ++i)
{
for(int j = 0; j < cols; ++j)
{
if(grid[i][j] != 0)
oranges++;
if(grid[i][j] == 2)
bfs.push({i, j});
}
}
if(oranges == 0)
return 0;
while(!bfs.empty())
{
int current = bfs.size();
rot += current;
if(rot == oranges)
return ans;
while(current--)
{
int curr_x = bfs.front().first;
int curr_y = bfs.front().second;
bfs.pop();
for(auto i: direction)
{
int x = curr_x + i.first;
int y = curr_y + i.second;
if(x < 0 || y < 0 || x >= rows || y >= cols || grid[x][y] == 0 || grid[x][y] == 2)
continue;
else
{
grid[x][y] = 2;
bfs.push({x, y});
}
}
}
ans++;
}
return -1;
}
};