/
main.go
135 lines (107 loc) · 2.56 KB
/
main.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
package main
import (
"fmt"
"log"
"os"
"strconv"
"strings"
"github.com/TomasCruz/projecteuler"
)
/*
Problem 18; Maximum path sum I
By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total
from top to bottom is 23.
3
7 4
2 4 6
8 5 9 3
That is, 3 + 7 + 4 + 9 = 23.
Find the maximum total from top to bottom of the triangle below:
75
95 64
17 47 82
18 35 87 10
20 04 82 47 65
19 01 23 75 03 34
88 02 77 73 07 63 67
99 65 04 28 06 16 70 92
41 41 26 56 83 40 80 70 33
41 48 72 33 47 32 37 16 94 29
53 71 44 65 25 43 91 52 97 51 14
70 11 33 28 77 73 17 78 39 68 17 57
91 71 52 38 17 14 91 43 58 50 27 29 48
63 66 04 68 89 53 67 30 73 16 69 87 40 31
04 62 98 27 23 09 70 98 73 93 38 53 60 04 23
NOTE: As there are only 16384 routes, it is possible to solve this problem by trying every route.
However, Problem 67, is the same challenge with a triangle containing one-hundred rows; it cannot be solved by brute force,
and requires a clever method! ;o)
*/
func main() {
var limit int
if len(os.Args) > 1 {
limit64, err := strconv.ParseInt(os.Args[1], 10, 64)
if err != nil {
log.Fatal("bad argument")
}
limit = int(limit64)
} else {
limit = 15
}
projecteuler.Timed(calc, limit)
}
func calc(args ...interface{}) (result string, err error) {
limit := args[0].(int)
var textNumbers []string
if textNumbers, err = projecteuler.FileToStrings("input.txt"); err != nil {
fmt.Println(err)
return
}
var m [][]int
if m, err = buildMatrix(limit, textNumbers); err != nil {
return
}
resultMatrix := buildAddedMatrix(limit, m)
//projecteuler.PrintMatrix(resultMatrix)
result = strconv.Itoa(resultMatrix[0][0])
return
}
func buildMatrix(dim int, textNumbers []string) (m [][]int, err error) {
m = make([][]int, dim)
for i := 0; i < dim; i++ {
m[i] = make([]int, dim)
numStrings := strings.Split(textNumbers[i], " ")
var j int
for j = 0; j < len(numStrings); j++ {
input := strings.TrimLeftFunc(numStrings[j], func(r rune) bool { return r == '0' })
if m[i][j], err = strconv.Atoi(input); err != nil {
fmt.Println(err)
return
}
}
for ; j < dim; j++ {
m[i][j] = 0
}
}
return
}
func buildAddedMatrix(dim int, m [][]int) (dp [][]int) {
dp = make([][]int, dim)
for i := 0; i < dim; i++ {
dp[i] = make([]int, dim)
copy(dp[i], m[i])
}
for i := dim - 1; i > 0; i-- {
for j := 0; j <= i; j++ {
if j > 0 {
curr := dp[i][j] + m[i-1][j-1]
if curr > dp[i-1][j-1] {
dp[i-1][j-1] = curr
}
}
if j < i {
dp[i-1][j] = dp[i][j] + m[i-1][j]
}
}
}
return
}