2022-09-13 23:39:52 +02:00
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// Copyright 2022 wanderer <wanderer at dotya.ml>
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// SPDX-License-Identifier: GPL-3.0-or-later
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package main
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import (
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"log"
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"os"
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"strconv"
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"time"
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)
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type matrix struct {
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rows [][]int
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}
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// stoi attempts to convert a supposed int in string form to an actual int,
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// fails loudly if it doesn't work.
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func stoi(s string) int {
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val, err := strconv.Atoi(s)
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if err != nil {
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log.Fatalln("could not convert from string to int:", s, err)
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}
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return val
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}
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// rowtoi converts a row (a []string) to an []int and returns it.
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func rowtoi(row []string) []int {
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cols := len(row)
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// prealloc, when the size is known, gosimple is wrong here.
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intRow := make([]int, cols, cols) //nolint:gosimple
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for i, v := range row {
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intRow[i] = stoi(v)
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}
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return intRow
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}
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// isNonEmptyMatrix checks the [][]string input and determines whether it is a
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// non-empty matrix, since that is the kind we care about.
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func isNonEmptyMatrix(strmatrix [][]string) bool {
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initCols := len(strmatrix[0])
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if initCols == 0 || len(strmatrix) == 0 {
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log.Printf("emptymatrix: we don't want those")
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return false
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}
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for i, v := range strmatrix {
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cols := len(v)
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if cols != initCols {
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2022-09-13 23:42:01 +02:00
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log.Printf(
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"notamatrix: all rows until now were of '%d' columns\n"+
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"offending row: #%d, size: %d",
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initCols, i, cols,
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)
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2022-09-13 23:39:52 +02:00
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return false
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}
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}
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return true
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}
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func initMatrix(strmatrix [][]string) matrix {
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m := &matrix{}
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// we can now safely do this because at this point we have already checked
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// that strmatrix is a "valid" matrix.
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cols := len(strmatrix[0])
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rows := len(strmatrix)
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// prealloc, when the size is known, gosimple is wrong here.
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m.rows = make([][]int, rows, rows) //nolint:gosimple
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for i := range strmatrix {
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// prealloc, when the size is known, gosimple is wrong here.
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m.rows[i] = make([]int, cols, cols) //nolint:gosimple
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}
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return *m
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}
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// convertMatrix attempts to convert the whole string matrix to an int matrix.
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func convertMatrix(strmatrix [][]string) matrix {
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if !isNonEmptyMatrix(strmatrix) {
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log.Fatalln("bailing...")
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os.Exit(2)
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}
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m := initMatrix(strmatrix)
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for i, v := range strmatrix {
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m.rows[i] = rowtoi(v)
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}
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return m
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}
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// traverseMatrix traverses the given matrix in such a manner as to accumulate
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// the smallest possible sum. allowed movements are down and to the right.
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func traverseMatrixMinSumPath(m matrix) { //nolint:unparam
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// ad unparam: m will be used shortly.
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start := time.Now()
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log.Printf("traversing the matrix took: %s", time.Since(start))
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}
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