leetcode_c++：Merge_Intervals（056）

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].

算法

复杂度：O（nm）

#include<iostream>
#include<vector>
#include <algorithm>

using namespace std;

const int N=0;

struct Interval {
int start;
int end;
Interval() : start(0), end(0) {}
Interval(int s, int e) : start(s), end(e) {}
};

bool isLess(const Interval &a, const Interval &b){
return a.start<b.start;
}

class Solution{
public:
vector<Interval> merge(vector<Interval> &intervals){
int nSize=intervals.size();
vector<Interval>  result;
if(nSize==0)
return result;

sort(intervals.begin(),intervals.end(),isLess);
Interval val=intervals[0];
Interval next;
for(int i=1;i<nSize;++i){
next=intervals[i];
if(next.start>val.end){
result.push_back(val);
val=next;

}else{
val.end=val.end>next.end? val.end:next.end;
}

}

result.push_back(val);
return result;
}
};