小红的矩阵染色

实现代码：

 public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int k = sc.nextInt();
        
        char[][] grid = new char[n][];
        for (int i = 0; i < n; i++) {
            grid[i] = sc.next().toCharArray();
        }
        
        List<Integer> segments = new ArrayList<>();
        
        // 按列找空白段
        for (int col = 0; col < m; col++) {
            int len = 0;
            for (int row = 0; row < n; row++) {
                if (grid[row][col] == 'o') {
                    len++;
                } else { // '*'
                    if (len > 0) {
                        segments.add(len);
                        len = 0;
                    }
                }
            }
            if (len > 0) {
                segments.add(len);
            }
        }
        
        // 段长度从大到小排序
        segments.sort((a, b) -> b - a);
        
        int maxScore = 0;
        long prefixSum = 0;
        for (int p = 0; p < segments.size(); p++) {
            prefixSum += segments.get(p);
            long totalColored = Math.min(prefixSum, k);
            int score = (int)(totalColored - (p + 1)); // p+1 是段数
            if (score > maxScore) {
                maxScore = score;
            }
        }
        
        System.out.println(maxScore);
    }