b站后端开发笔经
不知道为什么编程题这么简单😂
1.四个数计算24
class Solution {
public:
/**
*
* @param arr int整型一维数组
* @param arrLen int arr数组长度
* @return bool布尔型
*/
bool process(int index,int i,int* arr,int arrLen,int path)
{
if (index == 4 && path == 24)
return true;
if (index == 4)
return false;
if (index == i)
return process(index + 1, i, arr, arrLen, path);
return process(index + 1, i, arr, arrLen, path + arr[index])||
process(index + 1, i, arr, arrLen, path - arr[index])||
process(index + 1, i, arr, arrLen, path * arr[index])||
arr[index]==0||process(index + 1, i, arr, arrLen, path / arr[index]);
}
bool Game24Points(int* arr, int arrLen) {
for (int i = 0; i < 4; i++)
{
if (process(0,i, arr, arrLen,arr[i]))
return true;
}
return false;
}
};
2.括号匹配
class Solution {
public:
/**
*
* @param s string字符串
* @return bool布尔型
*/
bool isvalid(stack<char> &st, char ch)
{
if (st.top() == '('&&ch == ')')
return true;
if (st.top() == '['&&ch == ']')
return true;
if (st.top() == '{'&&ch == '}')
return true;
return false;
}
bool IsValidExp(string s) {
if (s.size() == 0)
return true;
stack<char> st;
for (int i = 0; i < s.size(); i++)
{
if (st.empty() && (s[i] == ')' || s[i] == ']' || s[i] == '}'))
return false;
if (isvalid(st, s[i]))
st.pop();
else
{
st.push(s[i]);
}
}
return st.empty();
}
};
3.找零问题
因为就是个单纯的计算题，代码比较简单就不贴出来了
#笔经##哔哩哔哩#