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| func orangesRotting(grid [][]int) int {
m := len(grid)
n := len(grid[0])
queue := []int{}
fresh := 0
for i := 0; i < m; i++ {
for j := 0; j < n; j++ {
if grid[i][j] == 1 {
fresh++
} else if grid[i][j] == 2 {
queue = append(queue, i*n+j)
}
}
}
directions := [][]int{
{-1, 0},
{0, 1},
{1, 0},
{0, -1},
}
ans := 0
for len(queue) > 0 && fresh > 0 {
size := len(queue)
for i := 0; i < size; i++ {
sum := queue[i]
row := sum / n
col := sum - row*n
for _, direction := range directions {
newRow := row + direction[0]
newCol := col + direction[1]
if newRow >= 0 && newRow < m && newCol >= 0 && newCol < n && grid[newRow][newCol] == 1 {
fresh--
grid[newRow][newCol] = 2
queue = append(queue, newRow*n+newCol)
}
}
}
queue = queue[size:]
ans++
}
if fresh > 0 {
return -1
}
return ans
}
|
