-
-
Notifications
You must be signed in to change notification settings - Fork 299
/
417.java
138 lines (104 loc) · 4.28 KB
/
417.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
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
__________________________________________________________________________________________________
sample 2 ms submission
class Solution {
private static final int[][] dirs = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
public List<int[]> pacificAtlantic(int[][] matrix) {
List<int[]> answer = new ArrayList<>();
if ( matrix == null || matrix.length == 0 ) return answer;
int N = matrix.length;
int M = matrix[0].length;
char[][] visited = new char[N][M];
// Columns Pacific
for (int c = 0; c < M; c++)
dfs(matrix, 0, c, visited, 'P', answer);
// Rows Pacific
for (int r = 0; r < N; r++)
dfs(matrix, r, 0, visited, 'P', answer);
// Columns Atlantic
for (int c = 0; c < M; c++)
dfs(matrix, N-1, c, visited, 'A', answer);
// Rows Atlantic
for (int r = 0; r < N; r++)
dfs(matrix, r, M-1, visited, 'A', answer);
return answer;
}
private void dfs(int[][] matrix, int r, int c, char[][] visited, char ch, List<int[]> answer) {
if ( visited[r][c] == 'P' && ch == 'A' ) answer.add(new int[]{r, c});
visited[r][c] = ch;
for ( int[] d : dirs ) {
int nx = r + d[0];
int ny = c + d[1];
if ( nx < 0 || nx >= matrix.length || ny < 0 || ny >= matrix[0].length || matrix[r][c] > matrix[nx][ny] || visited[nx][ny] == ch )
continue;
dfs(matrix, nx, ny, visited, ch, answer);
}
}
}
__________________________________________________________________________________________________
sample 39664 kb submission
import java.util.*;
class Solution {
private int[][] directions = new int[][] {{1, 0}, {-1, 0}, {0, -1}, {0, 1}};
public List<int[]> pacificAtlantic(int[][] matrix) {
if (matrix == null || matrix.length == 0 || matrix[0] == null || matrix[0].length == 0) {
return new ArrayList();
}
int m = matrix.length;
int n = matrix[0].length;
boolean[][] atlantic = new boolean[m][n];
boolean[][] pacific = new boolean[m][n];
// pacific fist
PriorityQueue<int[]> queue = new PriorityQueue<>((a, b) -> (a[2] - b[2]));
for (int i=0; i<m; i++) {
queue.add(new int[] {i, 0, matrix[i][0]});
pacific[i][0] = true;
}
for (int j=1; j<n; j++) {
queue.add(new int[] {0, j, matrix[0][j]});
pacific[0][j] = true;
}
while (!queue.isEmpty()) {
int[] cur = queue.poll();
for (int[] direction : directions) {
int x = cur[0] + direction[0];
int y = cur[1] + direction[1];
if (x < 0 || y < 0 || x == m || y == n || pacific[x][y] || matrix[x][y] < cur[2]) {
continue;
}
queue.add(new int[]{x, y, matrix[x][y]});
pacific[x][y] = true;
}
}
queue.clear();
for (int i=0; i<m; i++) {
queue.add(new int[] {i, n-1, matrix[i][n-1]});
atlantic[i][n-1] = true;
}
for (int j=n-2; j>=0; j--) {
queue.add(new int[] {m-1, j, matrix[m-1][j]});
atlantic[m-1][j] = true;
}
while (!queue.isEmpty()) {
int[] cur = queue.poll();
for (int[] direction : directions) {
int x = cur[0] + direction[0];
int y = cur[1] + direction[1];
if (x < 0 || y < 0 || x == m || y == n || atlantic[x][y] || matrix[x][y] < cur[2]) {
continue;
}
queue.add(new int[]{x, y, matrix[x][y]});
atlantic[x][y] = true;
}
}
List<int[]> res = new ArrayList();
for (int i=0; i<m; i++) {
for (int j=0; j<n; j++) {
if (pacific[i][j] && atlantic[i][j]) {
res.add(new int[] {i, j});
}
}
}
return res;
}
}
__________________________________________________________________________________________________