LeetCode 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].

题意：去掉反复的区间。

思路：排序后，再比較end的情况。

/**
 * Definition for an interval.
 * struct Interval {
 *     int start;
 *     int end;
 *     Interval() : start(0), end(0) {}
 *     Interval(int s, int e) : start(s), end(e) {}
 * };
 */
 bool cmp(const Interval &a, const Interval &b) {
    return a.start < b.start;
 }

class Solution {
public:
    vector<Interval> merge(vector<Interval> &intervals) {
        int n = intervals.size();

        vector<Interval> ans;
        sort(intervals.begin(), intervals.end(), cmp);
        for (int i = 0; i < intervals.size(); i++) {
            if (ans.size() == 0) ans.push_back(intervals[i]);
            else {
                int m = ans.size();
                if (ans[m-1].start <= intervals[i].start && ans[m-1].end >= intervals[i].start) 
                    ans[m-1].end = max(ans[m-1].end, intervals[i].end);
                else ans.push_back(intervals[i]);
            }
        }

        return ans;
    }
};