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### by Sumit Chourasia | Oct 01, 2020 | Category :coding | Tags : algorithmdata-structureeasyleetcodemaths #### Day of the Year - Math - Easy - LeetCode

Given a string date representing a Gregorian calendar date formatted as YYYY-MM-DD, return the day number of the year.

Example 1:

Input: date = "2019-01-09"
Output: 9
Explanation: Given date is the 9th day of the year in 2019.
Example 2:

Input: date = "2019-02-10"
Output: 41
Example 3:

Input: date = "2003-03-01"
Output: 60
Example 4:

Input: date = "2004-03-01"
Output: 61

Constraints:

date.length == 10
date == date == '-', and all other date[i]'s are digits
date represents a calendar date between Jan 1st, 1900 and Dec 31, 2019.

``````public class Solution {
public int DayOfYear(string date) {
var arr = date.Split('-');
bool isLeap = checkYear(int.Parse(arr));
var months = new int[]{31,28,31,30,31,30,31,31,30,31,30,31};
int count = 0;
for(int i=0;i<int.Parse(arr)-1;i++){
if(isLeap && i==1){
count+=1;
}
count+=months[i];
}
count+=int.Parse(arr);

return count;
}

private bool checkYear(int year){
if(year%400==0){
return true;
}

if(year%100==0){
return false;
}

if( year %4 == 0){
return true;
}
return false;
}
}``````

Time Complexity: O(1)

Space Complexity: O(1)