Hard 57题 Insert Interval

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Question：

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].

solution:

看了思路后写了一个LTE的。。

/** * Definition for an interval. * public class Interval { *     int start; *     int end; *     Interval() { start = 0; end = 0; } *     Interval(int s, int e) { start = s; end = e; } * } */public class Solution {    public List<Interval> insert(List<Interval> intervals, Interval newInterval) {        intervals.add(newInterval);        int n=intervals.size();        int i=0;        int j=0;        //sort with start        for(i=0;i<=n-2;i++)        {               for(j=i+1;j<=n-1;j++)            {                 if(intervals.get(i).start>intervals.get(j).start)                 {                     Interval tmp=intervals.get(i);                     intervals.set(i,intervals.get(j));                     intervals.set(j,tmp);                 }            }        }           //take the first interval and compare its end with the next interval starts        for(i=0;i<=n-2;i++)        {            if(intervals.get(i).end>intervals.get(i+1).start&&(intervals.get(i).end<=intervals.get(i+1).end))            {                 Interval tmp=new Interval(intervals.get(i).start,intervals.get(i+1).start);                 intervals.set(i,tmp);            }              if(intervals.get(i).end>intervals.get(i+1).start&&(intervals.get(i).end<=intervals.get(i+1).end))            {                 Interval tmp=new Interval(intervals.get(i).start,intervals.get(i+1).start);                 intervals.set(i,tmp);            }                       }        //combine two interval if its end is the same as the next interval's start        for(i=n-1;i>=1;i--)        {            if(intervals.get(i).start==intervals.get(i-1).end)            {                 Interval tmp=new Interval(intervals.get(i-1).start,intervals.get(i).end);                 intervals.remove(i);                 intervals.set(i-1,tmp);            }        }        return intervals;    }}

修改了下插入那里，就过了~但还有更好的方法

/** * Definition for an interval. * public class Interval { *     int start; *     int end; *     Interval() { start = 0; end = 0; } *     Interval(int s, int e) { start = s; end = e; } * } */public class Solution {    public List<Interval> insert(List<Interval> intervals, Interval newInterval) {        intervals.add(newInterval);        int n=intervals.size();        int i=0;        int j=0;        //sort with start,to find where to put the newinterval        for(i=n-2;i>=0;i--)        {               if(intervals.get(n-1).start>=intervals.get(i).start)                    break;        }           int piv=i;        //add the new interval        for(i=n-1;i>=piv+2;i--)        {            intervals.set(i,intervals.get(i-1));        }        intervals.set(piv+1,newInterval);        //take the first interval and compare its end with the next interval starts        for(i=0;i<=n-2;i++)        {            if(intervals.get(i).end>intervals.get(i+1).start&&(intervals.get(i).end<=intervals.get(i+1).end))            {             //    Interval tmp=new Interval(intervals.get(i).start,intervals.get(i+1).start);                 intervals.set(i,new Interval(intervals.get(i).start,intervals.get(i+1).start));            }            if(intervals.get(i).end>intervals.get(i+1).start&&(intervals.get(i).end>intervals.get(i+1).end))            {            //     Interval tmp=new Interval(intervals.get(i).end,intervals.get(i).end);                 intervals.set(i+1,new Interval(intervals.get(i).end,intervals.get(i).end));            }                       }        //combine two interval if its end is the same as the next interval's start        for(i=n-1;i>=1;i--)        {            if(intervals.get(i).start==intervals.get(i-1).end)            {                // Interval tmp=new Interval(intervals.get(i-1).start,intervals.get(i).end);                 intervals.set(i-1,new Interval(intervals.get(i-1).start,intervals.get(i).end));                 intervals.remove(i);            }        }        return intervals;    }}

public class Solution {    public List<Interval> insert(List<Interval> intervals, Interval newInterval) {        List<Interval> ans=new LinkedList<>();        int n=intervals.size();        int i=0;        //put the unrevelvant item into the ans        while(i<=n-1&&intervals.get(i).end<newInterval.start)            ans.add(intervals.get(i++));        //change the newInterval        while(i<=n-1&&intervals.get(i).start<=newInterval.end)        {            newInterval=new Interval(                Math.min(intervals.get(i).start,newInterval.start),                Math.max(intervals.get(i).end, newInterval.end));            i++;        }        ans.add(newInterval);        while(i<=n-1)            ans.add(intervals.get(i++));        return ans;    }}

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