LeetCode 56:Merge Intervals

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]

.

分析：

题目要求对区间进行合并，首先必须对区间按照左边元素的大小进行排序，然后对排序后的数组进行遍历，合并。

能够合并的区间必须符合 a.begin <=b.begin <= a.end.

代码如下：

/**
 * Definition for an interval.
 * struct Interval {
 *     int start;
 *     int end;
 *     Interval() : start(0), end(0) {}
 *     Interval(int s, int e) : start(s), end(e) {}
 * };
 */
class Solution {
    
public:
 
    static int compare_Interval(Interval val1, Interval val2){
    
        return val1.start < val2.start;
    }
    vector<Interval> merge(vector<Interval>& intervals) {
        vector<Interval> result;
        
        if (intervals.size()<=1) {
            return  intervals;
        }
        sort(intervals.begin(),intervals.end(),  compare_Interval);
        Interval node = intervals[0] ;
        for (int index=1; index<intervals.size(); index++) {
            Interval tmp = intervals[index] ;
            if (tmp.start > node.end) {
                result.push_back(node);
                node = tmp;
                continue;
            }else{
                node.end = max(tmp.end, node.end);
            }
        }
        result.push_back(node);
        return result;
    }

};