高频题（0）
1. shortest distance to 1
"给一个input array eg：［1，0，0，1，0，1，0，0，1]
output [0，1，1，０，1，０，1，1，０]
找每个element 他离1最近的距离"
output [0，1，1，０，1，０，1，1，０]
找每个element 他离1最近的距离"
2. Basic Calculator with Parentheses and Integer Division
Implement a basic calculator to evaluate a simple expression string.
The expression string contains only non-negative integers, '+', '-', '*', '/' operators, and open '(' and closing parentheses ')'. The integer division should truncate toward zero.
You may assume that the given expression is always valid. All intermediate results will be in the range of [-231, 231 - 1].
Note: You are not allowed to use any built-in function which evaluates strings as mathematical expressions, such as eval().
Example 1:
Input: s = "1+1"
Output: 2
Example 2:
Input: s = "6-4/2"
Output: 4
Example 3:
Input: s = "2*(5+5*2)/3+(6/2+8)"
Output: 21
Constraints:
1 <= s <= 104
s consists of digits, '+', '-', '*', '/', '(', and ')'.
s is a valid expression.
The expression string contains only non-negative integers, '+', '-', '*', '/' operators, and open '(' and closing parentheses ')'. The integer division should truncate toward zero.
You may assume that the given expression is always valid. All intermediate results will be in the range of [-231, 231 - 1].
Note: You are not allowed to use any built-in function which evaluates strings as mathematical expressions, such as eval().
Example 1:
Input: s = "1+1"
Output: 2
Example 2:
Input: s = "6-4/2"
Output: 4
Example 3:
Input: s = "2*(5+5*2)/3+(6/2+8)"
Output: 21
Constraints:
1 <= s <= 104
s consists of digits, '+', '-', '*', '/', '(', and ')'.
s is a valid expression.
3. 最短路径
Find a shortest vertical path from the first row to bottom row in a 2D matrix
DP解决
4. Code review
What is the output of the following code?
int main()
{
int a, b, c;
a = 9;
c = a + 1 + 1 * 0;
b = c++;
printf("a: %d, b: %d, c: %d\n", a, b, c);
return 0;
}
5. Find a unique integer in a list of duplicates
Given a list of integers where each integer, except one, appears twice. Find the one integer that only appears once.
最后希望O(n) time, O(1) space
