/
AsFarFromLandAsPossible.java
50 lines (43 loc) · 1.41 KB
/
AsFarFromLandAsPossible.java
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
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
// https://leetcode.com/problems/as-far-from-land-as-possible/
class Solution {
public int maxDistance(int[][] grid) {
int res = 0;
while (true) {
if (populate(grid)) {
res++;
} else {
break;
}
}
return res == 0 ? -1 : res;
}
boolean safePut(int[][] grid, int i, int j, int val) {
if (i < 0 || i >= grid.length) return false;
if (j < 0 || j >= grid[i].length) return false;
if (grid[i][j] == val || grid[i][j] == -val) return false;
grid[i][j] = val;
return true;
}
boolean populate(int[][] grid) {
boolean res = false;
for (int i = 0; i < grid.length; i++) {
for (int j = 0; j < grid[i].length; j++) {
if (grid[i][j] == 1) {
boolean left = safePut(grid, i, j - 1, -1);
boolean right = safePut(grid, i, j + 1, -1);
boolean top = safePut(grid, i - 1, j, -1);
boolean bottom = safePut(grid, i + 1, j, -1);
res |= top || bottom || left || right;
}
}
}
for (int i = 0; i < grid.length; i++) {
for (int j = 0; j < grid[i].length; j++) {
if (grid[i][j] == -1) {
grid[i][j] = 1;
}
}
}
return res;
}
}