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2 | 2 |
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3 | 3 | import java.util.Arrays;
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4 | 4 |
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5 |
| -/** |
6 |
| - * 85. Maximal Rectangle |
7 |
| - * |
8 |
| - * Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing only 1's and return its area. |
9 |
| -
|
10 |
| - For example, given the following matrix: |
11 |
| -
|
12 |
| - 1 0 1 0 0 |
13 |
| - 1 0 1 1 1 |
14 |
| - 1 1 1 1 1 |
15 |
| - 1 0 0 1 0 |
16 |
| - Return 6. |
17 |
| -
|
18 |
| - */ |
19 | 5 | public class _85 {
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20 |
| - public static class Solution1 { |
21 |
| - public int maximalRectangle(char[][] matrix) { |
22 |
| - if (matrix.length == 0) { |
23 |
| - return 0; |
24 |
| - } |
25 |
| - int m = matrix.length; |
26 |
| - int n = matrix[0].length; |
27 |
| - int[] left = new int[n]; |
28 |
| - int[] right = new int[n]; |
29 |
| - int[] height = new int[n]; |
30 |
| - Arrays.fill(left, 0); |
31 |
| - Arrays.fill(right, n); |
32 |
| - Arrays.fill(height, 0); |
33 |
| - int maxA = 0; |
34 |
| - for (int i = 0; i < m; i++) { |
35 |
| - int currLeft = 0; |
36 |
| - int currRight = n; |
37 |
| - |
38 |
| - //compute height, this can be achieved from either side |
39 |
| - for (int j = 0; j < n; j++) { |
40 |
| - if (matrix[i][j] == '1') { |
41 |
| - height[j]++; |
42 |
| - } else { |
43 |
| - height[j] = 0; |
44 |
| - } |
45 |
| - } |
46 |
| - |
47 |
| - //compute left, from left to right |
48 |
| - for (int j = 0; j < n; j++) { |
49 |
| - if (matrix[i][j] == '1') { |
50 |
| - left[j] = Math.max(left[j], currLeft); |
51 |
| - } else { |
52 |
| - left[j] = 0; |
53 |
| - currLeft = j + 1; |
54 |
| - } |
55 |
| - } |
56 |
| - |
57 |
| - //compute right, from right to left |
58 |
| - for (int j = n - 1; j >= 0; j--) { |
59 |
| - if (matrix[i][j] == '1') { |
60 |
| - right[j] = Math.min(right[j], currRight); |
61 |
| - } else { |
62 |
| - right[j] = n; |
63 |
| - currRight = j; |
64 |
| - } |
65 |
| - } |
66 |
| - |
67 |
| - //compute rectangle area, this can be achieved from either side |
68 |
| - for (int j = 0; j < n; j++) { |
69 |
| - maxA = Math.max(maxA, (right[j] - left[j]) * height[j]); |
| 6 | + public static class Solution1 { |
| 7 | + public int maximalRectangle(char[][] matrix) { |
| 8 | + if (matrix.length == 0) { |
| 9 | + return 0; |
| 10 | + } |
| 11 | + int m = matrix.length; |
| 12 | + int n = matrix[0].length; |
| 13 | + int[] left = new int[n]; |
| 14 | + int[] right = new int[n]; |
| 15 | + int[] height = new int[n]; |
| 16 | + Arrays.fill(left, 0); |
| 17 | + Arrays.fill(right, n); |
| 18 | + Arrays.fill(height, 0); |
| 19 | + int maxA = 0; |
| 20 | + for (int i = 0; i < m; i++) { |
| 21 | + int currLeft = 0; |
| 22 | + int currRight = n; |
| 23 | + |
| 24 | + //compute height, this can be achieved from either side |
| 25 | + for (int j = 0; j < n; j++) { |
| 26 | + if (matrix[i][j] == '1') { |
| 27 | + height[j]++; |
| 28 | + } else { |
| 29 | + height[j] = 0; |
| 30 | + } |
| 31 | + } |
| 32 | + |
| 33 | + //compute left, from left to right |
| 34 | + for (int j = 0; j < n; j++) { |
| 35 | + if (matrix[i][j] == '1') { |
| 36 | + left[j] = Math.max(left[j], currLeft); |
| 37 | + } else { |
| 38 | + left[j] = 0; |
| 39 | + currLeft = j + 1; |
| 40 | + } |
| 41 | + } |
| 42 | + |
| 43 | + //compute right, from right to left |
| 44 | + for (int j = n - 1; j >= 0; j--) { |
| 45 | + if (matrix[i][j] == '1') { |
| 46 | + right[j] = Math.min(right[j], currRight); |
| 47 | + } else { |
| 48 | + right[j] = n; |
| 49 | + currRight = j; |
| 50 | + } |
| 51 | + } |
| 52 | + |
| 53 | + //compute rectangle area, this can be achieved from either side |
| 54 | + for (int j = 0; j < n; j++) { |
| 55 | + maxA = Math.max(maxA, (right[j] - left[j]) * height[j]); |
| 56 | + } |
| 57 | + } |
| 58 | + return maxA; |
70 | 59 | }
|
71 |
| - } |
72 |
| - return maxA; |
73 | 60 | }
|
74 |
| - } |
75 | 61 | }
|
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