合并区间

<pre name="code" class="cpp">/**
 * Definition of Interval:
 * classs Interval {
 *     int start, end;
 *     Interval(int start, int end) {
 *         this->start = start;
 *         this->end = end;
 *     }
 */
class Solution {
public:
    static bool compare(const Interval &a, const Interval &b)  
    {  
        return a.start < b.start;  
    } // 规定了下面intervals进行排序（sort）时遵循的规则，即根据start升序排列
    /**
     * @param intervals: interval list.
     * @return: A new interval list.
     */
    vector<Interval> merge(vector<Interval> &intervals) {
        // write your code here
        vector<Interval> result;
        int n = intervals.size();
        if(n < 1){
            return result;
        }
        sort(intervals.begin(), intervals.end(), compare);  //根据start升序排列
        int left  = intervals[0].start;
        int right = intervals[0].end;
        for(int i = 1; i < n; i++){
            if(right >= intervals[i].start){
                right = max(right,intervals[i].end);
            }
            else{
                result.push_back(Interval(left, right));  
                left = intervals[i].start;  
                right = intervals[i].end; 
            }
        }
        result.push_back(Interval(left, right)); //!!!注意的地方
        return result;
    }
};