二进制搜索
SortedList.Keys集合。
开始了。这是O（log n ）：
private static int BinarySearch<T>(IList<T> list, T value){ if (list == null) throw new ArgumentNullException("list"); var comp = Comparer<T>.Default; int lo = 0, hi = list.Count - 1; while (lo < hi) { int m = (hi + lo) / 2; // this might overflow; be careful. if (comp.Compare(list[m], value) < 0) lo = m + 1; else hi = m - 1; } if (comp.Compare(list[lo], value) < 0) lo++; return lo;}public static int FindFirstIndexGreaterThanOrEqualTo<T,U> (this SortedList<T,U> sortedList, T key){ return BinarySearch(sortedList.Keys, key);}
