代码随想录算法训练营第三十一天 | 56. 合并区间、738.单调递增的数字

56. 合并区间

力扣题目链接

class Solution {
    public int[][] merge(int[][] intervals) {
        if (intervals.length <= 1) return intervals;
        List<int[]> result = new ArrayList<>();
        Arrays.sort(intervals, Comparator.comparingInt(a -> a[0]));
        int start = intervals[0][0];
        int end = intervals[0][1];
        for (int i = 1; i < intervals.length; i++) {
            if (intervals[i][0] > end) {
                result.add(new int[]{start, end});
                start = intervals[i][0];
                end = intervals[i][1];
            } else {
                end = Math.max(end, intervals[i][1]);
            }
        }
        result.add(new int[]{start, end});
        return result.toArray(new int[result.size()][]);
    }
}

738.单调递增的数字

力扣题目链接

class Solution {
    public int monotoneIncreasingDigits(int n) {
        char[] chars = String.valueOf(n).toCharArray();
        int len = chars.length;
        int index = len - 1;
        for (int i = len - 2; i >= 0; i--) {
            if (chars[i] > chars[i + 1]) {
                chars[i]--;
                index = i;
            }
        }
        for (int i = index + 1; i < len; i++) {
            chars[i] = '9';
        }
        return Integer.parseInt(new String(chars));
    }
}