LeetCode Online Judge 题目C# 练习 - Insert Interval

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].

  1 public struct Interval
  2         {
  3             public int start;
  4             public int end;
  5 
  6             public Interval(int s, int e)
  7             {
  8                 start = s;
  9                 end = e;
 10             }
 11         }
 12 
 13         public static List<Interval> InsertInterval(List<Interval> intervals, Interval newInterval)
 14         {
 15             int newS = -1;
 16             int newE = -1;
 17             List<Interval> ret = new List<Interval>();
 18 
 19             if (intervals.Count == 0)
 20             {
 21                 ret.Add(newInterval);
 22                 return ret;
 23             }
 24            
 25 
 26             if (newInterval.end < intervals[0].start)
 27             {
 28                 ret.Add(newInterval);
 29                 foreach (var item in intervals)
 30                 {
 31                     ret.Add(item);
 32                 }
 33                 return ret;
 34             }
 35 
 36             if (newInterval.start > intervals[intervals.Count - 1].end)
 37             {
 38                 foreach (var item in intervals)
 39                 {
 40                     ret.Add(item);
 41                 }
 42                 ret.Add(newInterval);
 43                 return ret;
 44             }
 45 
 46             if (newInterval.start <= intervals[0].start && newInterval.end >= intervals[intervals.Count - 1].end)
 47             {
 48                 ret.Add(newInterval);
 49                 return ret;
 50             }
 51 
 52             if (newInterval.start <= intervals[0].start)
 53             {
 54                 newS = newInterval.start;
 55                 foreach (var item in intervals)
 56                 {
 57                     if (newInterval.end > item.end)
 58                     {
 59                         continue;
 60                     }
 61                     if (newE == -1 && newInterval.end >= item.start && newInterval.end <= item.end)
 62                     {
 63                         newE = item.end;
 64                         ret.Add(new Interval(newS, newE));
 65                         continue;
 66                     }
 67                     if (newE == -1 && newInterval.end < item.start)
 68                     {
 69                         newE = newInterval.end;
 70                         ret.Add(new Interval(newS, newE));
 71                         ret.Add(item);
 72                         continue;
 73                     }
 74                     ret.Add(item);
 75                 }
 76                 return ret;
 77             }
 78 
 79             if (newInterval.end >= intervals[intervals.Count - 1].end)
 80             {
 81                 newE = newInterval.end;
 82                 foreach (var item in intervals)
 83                 {
 84                     if (newInterval.start > item.end)
 85                     {
 86                         ret.Add(item);
 87                         continue;
 88                     }
 89                     if (newS == -1 && newInterval.start >= item.start && newInterval.start <= item.end)
 90                     {
 91                         newS = item.start;
 92                         ret.Add(new Interval(newS, newE));
 93                         return ret;
 94                     }
 95                     if (newS == -1 && newInterval.start < item.start)
 96                     {
 97                         newS = newInterval.start;
 98                         ret.Add(new Interval(newS, newE));
 99                         return ret;
100                     }
101                 }
102                 return ret;
103             }
104 
105             foreach (var item in intervals)
106             {
107                 if (newS == -1 && newInterval.start < item.start)
108                 {
109                     newS = newInterval.start;
110                     continue;
111                 }
112                 if (newS == -1 && newInterval.start >= item.start && newInterval.start <= item.end)
113                 {
114                     newS = item.start;
115                     continue;
116                 }
117                 if (newS == -1 && newInterval.start > item.end)
118                 {
119                     ret.Add(item);
120                 }
121 
122                 if (newInterval.end > item.end)
123                 {
124                     continue;
125                 }
126                 if (newE == -1 && newInterval.end >= item.start && newInterval.end <= item.end)
127                 {
128                     newE = item.end;
129                     ret.Add(new Interval(newS, newE));
130                     continue;
131                 }
132                 if (newE == -1 && newInterval.end < item.start)
133                 {
134                     newE = newInterval.end;
135                     ret.Add(new Interval(newS, newE));
136                     ret.Add(item);
137                     continue;
138                 }
139 
140                 ret.Add(item);
141             }
142 
143             return ret;
144         }

 

代码分析：

　　分6种情况：

　　1. [0,1] [2,3] [5,6] [8,9]

　　2. [2,3] [5,6] [8,9] [10,11]

　　3. [1,                    10]

　　　　[2,3] [5,6] [8,9]

　　4. [1,    4]

　　　　[2,3] [5,6] [8,9]

　　5. 　　　　　　[7,   10]

　　　　[2,3] [5,6] [8,9]

　　6.　　  [4,      7]

　　　　[2,3] [5,6] [8,9]

posted @ 2012-09-13 22:00  ETCOW  阅读(622)  评论(0)  编辑  收藏  举报