p56

发表于 | 分类于 |

LeetCode p56 Merge Intervals 题解

1.题目：

Given a collection of intervals, merge all overlapping intervals.

For example,
Given [1,3],[2,6],[8,10],[15,18],
return [1,6],[8,10],[15,18].

题意：

合并所有重叠部分。

2.解题思路:

先排序再覆盖，见代码。

3.代码

[title] [] [url] [link text]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
 
/**
 * Definition for an interval.
 * public class Interval {
 *     int start;
 *     int end;
 *     Interval() { start = 0; end = 0; }
 *     Interval(int s, int e) { start = s; end = e; }
 * }
 */
public class Solution {
    public List<Interval> merge(List<Interval> intervals) {
        List<Interval> ans = new ArrayList<Interval>();
		if (intervals.size() < 1)
			return ans;
		Collections.sort(intervals, new Comparator<Interval>() {
			@Override
			public int compare(Interval a, Interval b) {
				return (int) (a.start - b.start);
			}
		});

		int start = intervals.get(0).start;
		int end = intervals.get(0).end;

		for (int i = 0; i < intervals.size() ; i++) {

			if (end >= intervals.get(i).start) {
				end = Math.max(intervals.get(i).end, end);

			} else {
				ans.add(new Interval(start, end));
				start = intervals.get(i).start;
				end = intervals.get(i).end;
			}
		}
		ans.add(new Interval(start, end));
		return ans;
    }
}

4.一些总结：