leetcode—有关区间合并

题目一：

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].

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 Array Sort

/** * Definition for an interval. * struct Interval { *     int start; *     int end; *     Interval() : start(0), end(0) {} *     Interval(int s, int e) : start(s), end(e) {} * }; */class Solution {public: static bool cmp(const Interval& a, const Interval& b)//升序排列 { return a.start < b.start; } vector<Interval> merge(vector<Interval>& intervals) { vector<Interval> res; int size = intervals.size(); if (size <= 0) return res; sort(intervals.begin(), intervals.end(), cmp); cout << size << endl; res.push_back(intervals[0]); for (int i = 0; i < size; ++i) { if (res.back().end >= intervals[i].start) res.back().end = (res.back().end>intervals[i].end ? res.back().end : intervals[i].end); else res.push_back(intervals[i]); } return res; }};

题目二：

Insert Intervals

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).

You may assume that the intervals were initially sorted according to their start times.

Example 1:
Given intervals [1,3],[6,9], insert and merge [2,5] in as [1,5],[6,9].

Example 2:
Given [1,2],[3,5],[6,7],[8,10],[12,16], insert and merge [4,9] in as [1,2],[3,10],[12,16].

This is because the new interval [4,9] overlaps with [3,5],[6,7],[8,10].

class Solution {public:    vector<Interval> insert(vector<Interval>& intervals, Interval newInterval) {        vector<Interval> res; int size = intervals.size(); if (size == 0) { res.push_back(newInterval); return res; } int i = 0; while (i < size) { if (newInterval.start>intervals[i].end) { res.push_back(intervals[i]); } else if (newInterval.end < intervals[i].start) { res.push_back(newInterval); while (i < size) { res.push_back(intervals[i]); i++; } return res; } else { newInterval.start = min(newInterval.start, intervals[i].start); newInterval.end = max(newInterval.end, intervals[i].end); } i++; } res.push_back(newInterval); return res;    }};