LeetCode56. 合并区间

题目传送地址: https://leetcode.cn/problems/merge-intervals/

运行效率:

代码如下:

class Solution {
  public static int[][] merge(int[][] intervals) {
   //先将区间项进行排序  因为区间项有可能是这样{{1,4},{0,4}}; 排序成{{0,4},{1,4}}
         Arrays.sort(intervals, Comparator.comparingInt(o -> o[0]));
        //处理边界情况
        if(intervals.length==1){
            return intervals;
        }
        List list = new ArrayList<>();
        int intervalStart = intervals[0][0]; //区间起点
        int intervalEnd = intervals[0][1]; //区间结尾
        for (int i = 1; i < intervals.length; i++) {
            int start = intervals[i][0];
            int end = intervals[i][1];
            if (intervalEnd >= start) {  //重叠情况  当前遍历项和区间出现重叠
            intervalEnd = Math.max(intervalEnd, end);            } else {  // 无重叠情况
                int[] interval = new int[2];
                interval[0] = intervalStart;
                interval[1] = intervalEnd;
                list.add(interval);
                intervalStart = start;
                intervalEnd = end;
            }
            if(i==intervals.length-1){  //遍历到最后一个区间项了
                int[] interval = new int[2];
                interval[0] = intervalStart;
                interval[1] = intervalEnd;
                list.add(interval);
            }
        }
        int[][] result = new int[list.size()][];
        result = list.toArray(result);
        return result;
    }
}