*Leetcode 57. Insert Interval

https://leetcode.com/problems/insert-interval/description/

应该是一道比较简单的hard题了

可能考的是对api的熟悉程度，不会api的比如我，就是排序在合并了

bool cmp(const Interval a, const Interval b) {
if (a.start != b.start) return a.start < b.start;
return a.end < b.end;
}
class Solution {
public:

vector<Interval> insert(vector<Interval>& intervals, Interval newInterval) {
vector<Interval> ret;
intervals.push_back(newInterval);
// if (intervals.size() == 0) return ret;

if (intervals.size() == 1) return intervals;
sort(intervals.begin(), intervals.end(), cmp);
Interval last = intervals[0];
for(int i = 1; i < intervals.size(); i++) {
if (last.end < intervals[i].start) { // no inter
ret.push_back(last);
last = intervals[i];
} else {
last.start = min(last.start, intervals[i].start);
last.end = max(last.end, intervals[i].end);
}
if (i == intervals.size() - 1) {
ret.push_back(last);
}
}

return ret;
}
};

然后写的比较漂亮的一个solution https://leetcode.com/problems/insert-interval/discuss/21599/
class Solution {
public:
vector<Interval> insert(vector<Interval>& intervals, Interval newInterval) {
auto compare = [] (const Interval &intv1, const Interval &intv2)
{ return intv1.end < intv2.start; };
auto range = equal_range(intervals.begin(), intervals.end(), newInterval, compare);
auto itr1 = range.first, itr2 = range.second;
if (itr1 == itr2) {
intervals.insert(itr1, newInterval);
} else {
itr2--;
itr2->start = min(newInterval.start, itr1->start);
itr2->end = max(newInterval.end, itr2->end);
intervals.erase(itr1, itr2);
}
return intervals;
}
};