CodeSignal 刷题 —— almostIncreasingSequence

Given a sequence of integers as an array, determine whether it is possible to obtain a strictly increasing sequence by removing no more than one element from the array.

Example

• For sequence = [1, 3, 2, 1], the output should be
  almostIncreasingSequence(sequence) = false.

  There is no one element in this array that can be removed in order to get a strictly increasing sequence.

• For sequence = [1, 3, 2], the output should be
  almostIncreasingSequence(sequence) = true.

  You can remove 3 from the array to get the strictly increasing sequence [1, 2]. Alternately, you can remove 2 to get the strictly increasing sequence [1, 3].

Input/Output

• [execution time limit] 0.5 seconds (cpp)

• [input] array.integer sequence

  Guaranteed constraints:
  2 ≤ sequence.length ≤ 105,
  -105 ≤ sequence[i] ≤ 105.

• [output] boolean

  • Return true if it is possible to remove one element from the array in order to get a strictly increasing sequence, otherwise return false.

Python3解法：

 import copy

 def isSequence(lst):
     for i in range(len(lst)):
         if lst.count(lst[i]) > 1:      #如果列表中有重复的数字，返回False
             return False
     sort_lst = copy.copy(lst)
     sort_lst.sort()
     if lst == sort_lst:
         return True
     else:
         return False

 def almostIncreasingSequence(sequence):
     if isSequence(sequence):
         return True
     i = 0
     while i < len(sequence):
         sequence_copy = copy.copy(sequence)
         del sequence_copy[i]                   # 循环，一个一个删除，查看剩余序列是否严格递增有序
         if isSequence(sequence_copy):
             return True
         i += 1

     return False

 print(almostIncreasingSequence([1,2,1,2]))

C++解法：

 bool isSequence(vector<int> sequence)
 {
     set<int>iset;
     for(auto e: sequence)
         iset.insert(e);
     if(iset.size() != sequence.size())     //如果sequence中有重复元素，返回false
         return false;

     vector<int>v = sequence;               //如果sequence与排序后的v相等，则说明sequence是递增有序的
     sort(v.begin(), v.end());
     if(sequence == v)
         return true;
     else
         return false;

 }

 bool almostIncreasingSequence(std::vector<int> sequence)
 {
     if (isSequence(sequence))
         return true;
     int i = ;
     while (i < sequence.size())
     {
         vector<int> v = sequence;
         v.erase(v.begin() + i);
         if(isSequence(v))
             return true;
         ++i;
     }
     return false;
 }