分析
注意细节处理就好
/**
* Definition of Interval:
* class Interval {
* int start, end;
* Interval(int start, int end) {
* this->start = start;
* this->end = end;
* }
*/
class Solution {
public:
/**
* @param intervals: interval list.
* @return: A new interval list.
*/
vector<Interval> merge(vector<Interval> &intervals) {
// write your code here
sort(intervals, 0, intervals.size() - 1);
vector<Interval> ret;
if (intervals.empty()) return ret;
Interval interval(intervals[0].start, intervals[0].end);
for (int i = 1; i < intervals.size(); ++i) {
if (intervals[i].start > interval.end) {
ret.push_back(interval);
interval.start = intervals[i].start;
interval.end = intervals[i].end;
} else {
interval.end = max(interval.end, intervals[i].end);
}
}
ret.push_back(interval);
return ret;
}
void sort(vector<Interval> &v, int bottom, int top) {
if (bottom >= top) return;
int i, j;
Interval interval = v[bottom];
i = bottom;
j = top;
while (i < j) {
for (; i < j && v[j].start >= interval.start; --j);
v[i] = v[j];
for (; i < j && v[i].start <= interval.start; ++i);
v[j] = v[i];
}
v[i] = interval;
sort(v, bottom, i - 1);
sort(v, i + 1, top);
}
};
