67: maximun path sum 2

67_maximum_path_sum_2/main.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	fi, err := os.Open("./triangle.txt")
+	if err != nil {
+		panic(err)
+	}
+	defer fi.Close()
+
+	br := bufio.NewReader(fi)
+	var input [][]int
+	for {
+		a, _, e := br.ReadLine()
+		if e == io.EOF {
+			break
+		}
+		got := strings.Split(string(a), " ")
+		var line []int
+		for _, v := range got {
+			n, err := strconv.Atoi(v)
+			if err != nil {
+				panic(err)
+			}
+			line = append(line, n)
+		}
+		input = append(input, line)
+	}
+	fmt.Println("input=", input)
+
+	fmt.Println("maximum path sum is:", LargestSumOfTriangle(input))
+}
+
+func LargestSumOfTriangle(input [][]int) int {
+	rest := input
+	l := len(input)
+	for l > 1 {
+		hl := l - 2
+		var line []int
+		for n, v := range input[l-2] {
+			x := v + max(input[l-1][n], input[l-1][n+1])
+			line = append(line, x)
+		}
+		rest = rest[:hl]
+		rest = append(rest, line)
+		l = len(rest)
+	}
+	return rest[0][0]
+}
+
+func max(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}