19

Author: faithByte

#19:Counting_Sundays.cpp

@@ -0,0 +1,66 @@
+#include <iostream>
+using namespace std;
+
+typedef unsigned long long ull;
+
+bool    isLeapYear(ull year)
+{
+    return (!(year % 4) && ((year % 100) || !(year % 400)));
+}
+
+short   getDayOfWeek(ull year, short month, short day)
+{
+    short   x;
+    
+    x = (14 - month)/12;
+    year -= x;
+    x = month + 12 * x - 2;
+    return ((day + year + year / 4 - year / 100 + year / 400 + (31 * x) / 12) % 7);
+}
+
+int main() {
+    ull     days, count, y[2];
+    short   q, M0, M1;
+    short   m[2], d[2];
+    short   daysPerMonth[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+    
+    cin >> q;
+    for (short i = 0; i < q; i++) {
+        // input
+        for (int j = 0; j < 2; j++) {
+            cin >> y[j];
+            cin >> m[j];
+            cin >> d[j];
+        }
+        
+        // get starting day
+        if (d[0] != 1)
+        {
+            m[0] = (m[0] + 1) % 13;
+            y[0] += (!m[0]);
+            m[0] += (!m[0]);
+        }
+        days = getDayOfWeek(y[0], m[0], 1);
+        
+        //  start counting        
+        count = 0;
+        M0 = m[0];
+        for (ull year = y[0]; year <= y[1]; year++) 
+        {
+            daysPerMonth[2] = 28 + isLeapYear(year);
+            M1 = 12 * (year != y[1]) + m[1] * (year == y[1]);
+            for (short month = M0; month <= M1; month++)
+            {   
+                if (!(days % 7))
+                {
+                    count++;
+                    days = 0;                    
+                }
+                days += daysPerMonth[month];
+            }
+            M0 = 1;
+        }
+        cout << count << endl;
+    }
+    return 0;
+}

README.md

@@ -80,3 +80,6 @@ ___
 ___
 ## <a href=https://www.hackerrank.com/contests/projecteuler/challenges/euler018/problem?isFullScreen> Problem 18: </a>  Maximum path sum I <sup>[Easy]</sup>
 Find the maximum sum of numbers that can be obtained by starting at the top of a triangle of numbers and moving to adjacent numbers on the row below, for a given triangle.
+___
+## <a href=https://www.hackerrank.com/contests/projecteuler/challenges/euler019/problem?isFullScreen> Problem 19: </a>  Counting Sundays <sup>[Easy]</sup>
+Find the number of Sundays that fell on the first of the month between two dates(both inclusive)