- 判断是否是数字
static bool isNumeric(string input)
{
bool flag = true;
string pattern = (@"^\d+$");
Regex validate = new Regex(pattern);
if (!validate.IsMatch(input))
{
flag = false;
}
return flag;
}
- 最简单的去重
for (int i = 0; i < list3.Count; i++)
{
if (list4.IndexOf(list3[i]) == -1)
{
list4.Add(list3[i]);
}
}
- 是否是回文
public bool isHuiwen(string bill)
{
int pos = 0;
Stack<string> ko = new Stack<string>();
bool isHui = true;
for (int i = 0; i < bill.Length; i++)
{
ko.Push(bill.Substring(i, 1));
}
while (ko.Count > 0)
{
string touding = ko.Pop();
if (touding != bill.Substring(pos, 1))
{
isHui = false;
break;
}
pos++;
}
return isHui;
}
- 时间复杂度从小到大
O(1)<O(logn)<O(n)<O(nlogn)<O(n^2)<O(n^3)<O(2^n)<O(n!)<O(n^n)
- 解决算法问题思路(画图抽象问题形象化 举例使抽象问题具体化 分解使复杂问题简单化)