Solved #28

pe28/pe28.go

@@ -0,0 +1,57 @@
+package pe28
+
+import (
+	"fmt"
+)
+
+type Matrix struct {
+	arr   []int
+	width int
+}
+
+func (m Matrix) GetIndex(row, col int) int {
+	return m.arr[m.width*row+col]
+}
+
+func (m *Matrix) SetIndex(row, col, val int) {
+	m.arr[m.width*row+col] = val
+}
+
+func (m Matrix) String() {
+	for row := 0; row < m.width; row++ {
+		fmt.Println(m.arr[row*m.width : row*m.width+m.width])
+	}
+}
+
+func Solve(_ []string) {
+	/*
+	   //width := 1001
+	   width := 10
+	   num_numbers := width * width
+	   mat := Matrix{
+	       arr: make([]int, num_numbers),
+	       width: width,
+	   }
+	   i := num_numbers
+	   cur_width
+	   for i > 0; {
+	       for y := width - 1; y >= 0; y-- {
+	           mat.SetIndex(x, y, i)
+	           i--
+	       }
+	   }
+	   //fmt.Println(mat)
+	   mat.String()
+	*/
+	max_width := 1001
+	sum := 1
+	for width := 1; width < max_width; width += 2 {
+		width_squared := width * width
+
+		sum += width_squared + width + 1 +
+			width_squared + 2*(width+1) +
+			width_squared + 3*(width+1) +
+			width_squared + 4*(width+1)
+	}
+	fmt.Println("Sum of diagonals =", sum)
+}

projecteuler.go

@@ -6,11 +6,13 @@ import (
 
 	"shillerben.com/gitlab/shillerben/projecteuler-go/pe26"
 	"shillerben.com/gitlab/shillerben/projecteuler-go/pe27"
+	"shillerben.com/gitlab/shillerben/projecteuler-go/pe28"
 )
 
 var solve_funcs = map[string]func([]string){
 	"26": pe26.Solve,
 	"27": pe27.Solve,
+	"28": pe28.Solve,
 }
 
 func main() {