LeetCode 57. 插入区间

几个注意点
1.原集合为空
2.插入在最开始的位置
3.插入在末尾位置
4.插入在中间

• 与前区间重叠但不与后区间重叠
• 不与前区间重叠但与后区间重叠
• 前后区间都重叠
• 前后区间都不重叠

可以通过添加标志，没有添加就每次都去判断重叠情况进行添加

vector insert(vector& intervals, Interval newInterval) {
    vector result ;
    if( intervals.size() == 0 ){
        result.push_back( newInterval );
        return result ;
    }
    bool isAdd = false ;
    for( int i = 0; i < intervals.size() ; i++ ){
        if( !isAdd ){
            if( intervals[i].start <= newInterval.start ){
                result.push_back( intervals[i] );
                if( newInterval.start <= intervals[i].end ){
                    result[result.size()-1].end = max(result[result.size()-1].end, newInterval.end );
                    isAdd = 1 ;
                }
            }
            else{
                if( result.size() > 0 && result[result.size()-1].end >= newInterval.start ){
                    result[result.size()-1].end = max(result[result.size()-1].end, newInterval.end );
                } else{
                    result.push_back( newInterval );
                }
                isAdd = 1 ;

                if( intervals[i].start <= newInterval.end ){
                    result[result.size()-1].end = max(result[result.size()-1].end, intervals[i].end );
                }
                else{
                    result.push_back(intervals[i]);
                }
            }
            continue ;
        }

        if( intervals[i].start <= result[result.size()-1].end ){
            result[result.size()-1].end = max(result[result.size()-1].end, intervals[i].end );
        }else{
            result.push_back( intervals[i] );
        }
    }
    if( !isAdd ){
        result.push_back( newInterval );
    }
    return result ;
}