leetcode 764. Largest Plus Sign | 764. 最大加号标志（Java）

雨点打透心脏的1/2处 2022-09-11 01:15 134阅读 0赞

## 题目 ##

[https://leetcode.com/problems/largest-plus-sign/][https_leetcode.com_problems_largest-plus-sign]  
![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16]

## 题解 ##

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 1]

class Solution { 
        public int orderOfLargestPlusSign(int n, int[][] mines) { 
            boolean[][] arr = new boolean[n][n];
            for (boolean[] a : arr) { 
                Arrays.fill(a, true);
            }
            for (int[] pair : mines) { 
                arr[pair[0]][pair[1]] = false;
            }
            int[][] ones = new int[n][n];
            // count ones left
            int count;
            for (int i = 0; i < n; i++) { 
                count = 0;
                for (int j = 0; j < n; j++) { 
                    if (arr[i][j]) count++;
                    else count = 0;
                    ones[i][j] = count;
                }
            }
            // count ones right
            for (int i = 0; i < n; i++) { 
                count = 0;
                for (int j = n - 1; j >= 0; j--) { 
                    if (arr[i][j]) count++;
                    else count = 0;
                    ones[i][j] = Math.min(ones[i][j], count);
                }
            }
            // count ones up
            for (int i = 0; i < n; i++) { 
                count = 0;
                for (int j = 0; j < n; j++) { 
                    if (arr[j][i]) count++;
                    else count = 0;
                    ones[j][i] = Math.min(ones[j][i], count);
                }
            }
            // count ones down
            for (int i = 0; i < n; i++) { 
                count = 0;
                for (int j = n - 1; j >= 0; j--) { 
                    if (arr[j][i]) count++;
                    else count = 0;
                    ones[j][i] = Math.min(ones[j][i], count);
                }
            }
    
            // find global max
            int max = Integer.MIN_VALUE;
            for (int i = 0; i < n; i++) { 
                for (int j = 0; j < n; j++) { 
                    max = Math.max(max, ones[i][j]);
                }
            }
            return max;
        }
    }

[https_leetcode.com_problems_largest-plus-sign]: https://leetcode.com/problems/largest-plus-sign/
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220829/774840b39a89411fb4fa63507cda12ce.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 1]: /images/20220829/33d6ff1428564c049e4d6c688f50d6ba.png