LeetCode: Merge Intervals http://oj.leetcode.com/problems/merge-intervals/

merge_intervals.cpp

/**
 * 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(Interval a, Interval b) {
    return a.start < b.start;
}

class Solution {
public:
    vector<Interval> merge(vector<Interval> &intervals) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        vector<Interval> res;
        sort(intervals.begin(), intervals.end(), cmp);
        
        int i = 0, len = intervals.size();
        while(i < len) {
            int j = i + 1;
            Interval tmp(intervals[i].start, intervals[i].end);
            while (j < len && intervals[j].start <= tmp.end) {
                tmp.end = std::max(intervals[j].end, tmp.end);
                j++;
            }
            res.push_back(tmp);
            i = j;
        }
        
        return res;
    }
};