LeetCode（56）Merge Intervals

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].

分析

给定几个区间，要求合并重叠区间，返回结果；

AC代码

/**
 * Definition for an interval.
 * struct Interval {
 *     int start;
 *     int end;
 *     Interval() : start(0), end(0) {}
 *     Interval(int s, int e) : start(s), end(e) {}
 * };
 */

//自定义Interval类型元素的升序比较函数
bool cmp(Interval a, Interval b)
{
    return a.start < b.start;
}

class Solution {
public: 

    vector<Interval> merge(vector<Interval>& intervals) {

        //如果输入参数为空，则返回空vector
        if (intervals.empty())
            return vector<Interval>();

        int len = intervals.size();
        //首先，按照每个Integerval的区间首值进行排序，自定义比较
        sort(intervals.begin(), intervals.end() , cmp);

        //声明结果
        vector<Interval> ret;
        vector<Interval>::iterator iter = intervals.begin();

        //定义临时变量
        Interval temp = intervals[0];

        for (int i = 0; i < len; i++)
        {
            //换一种判断方法
            if (intervals[i].start > temp.end)
            {
                ret.push_back(temp);
                temp = intervals[i];
            }
            else{
                temp.end = temp.end > intervals[i].end ? temp.end : intervals[i].end;
            }//else

        }//for
        ret.push_back(temp);
        return ret;
    }
};

GitHub测试程序源码