19

cmd/19/main.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main(){
+	weekday := time.Tuesday
+	sundays := 0
+	for i := 1901; i<=2000; i+=1 {
+		var leap int
+		if i%4 == 0 {
+			leap = 1
+		} else {
+			leap = 0
+		}
+
+		inYearOffset := 0
+		//january
+		if weekday == 0 {
+			sundays += 1
+		}
+		inYearOffset += 31
+		//feb
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 28 + leap
+		//march
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 31
+		//april
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 30
+		//may
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 31
+		//june
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 30
+		//july
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 31
+		//august
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 31
+		//september
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 30
+		//october
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 31
+		//november
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		inYearOffset += 30
+		//december
+		if (int(weekday) + inYearOffset) % 7 == 0 {
+			sundays += 1
+		}
+		fmt.Printf("%d: %d\n", i, inYearOffset + 31)
+
+
+		var offset int
+		if i % 4 == 0 {
+			offset = (366) % 7
+		} else {
+			offset = (365)  % 7
+		}
+		weekday = time.Weekday((offset + int(weekday)) % 7)
+	}
+
+	fmt.Printf("Sundays: %d\n", sundays)
+}