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LeetCode: Merge Intervals [055]

2024-07-05 20:31:53   222人阅读

【题目】


Given an array of non-negative integers, you are initially positioned at the first index of the array.

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].



【题意】

给定若干区间，把存在重叠的区间合并


【思路】

       

1. 先对区间按开始值一级升序排列，然后按照结束值二级升序排列
2. 对排序后的区间依次合并即可


【代码】

/**
 * 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 compare(const Interval&o1, const Interval&o2){
     if(o1.start<o2.start)return true;
     else if(o1.start==o2.start){
         return o1.end<o2.end;
     }
     return false;
 }
 
class Solution {
public:
    vector<Interval> merge(vector<Interval> &intervals) {
        vector<Interval> result;
        int size=intervals.size();
        if(size==0)return result;
        //排序
        sort(intervals.begin(), intervals.end(),compare);
        //合并
        Interval curInterval(intervals[0].start, intervals[0].end);
        for(int i=1; i<size; i++){
            if(curInterval.end<intervals[i].start){
                result.push_back(curInterval);
                curInterval=Interval(intervals[i].start, intervals[i].end);
            }
            else{
                if(intervals[i].end>curInterval.end)curInterval.end=intervals[i].end;
            }
        }
        //别忘了最后一个区间
        result.push_back(curInterval);
        return result;
    }
};


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