Solution to lossless-compression problem

lossless-compression.go

func losslessDataCompression(inputString string, width int) string {
    result := ""
    var i int = 0
    for i < len(inputString) {
        end := i + 1
        var begin int
        if i < width {
            begin = 0
        } else {
            begin = i - width
        }

        window := inputString[begin:end]

        var length int
    outer:
        for length = len(window); length > 0; length-- {
            for j := 0; j < len(window)-length; j++ {
                if i+length <= len(inputString) && inputString[i:i+length] == window[j:j+length] {
                    startIndex := i - len(window) + j + 1
                    pair := fmt.Sprintf("(%d,%d)", startIndex, length)
                    i += length
                    result += pair
                    break outer
                }
            }
        }
        if length == 0 {
            result += string(inputString[i])
            i++
        }
    }

    return result
}

lossless-compression_test.go

package main

import (
    "testing"
)

func TestLosslessComp(t *testing.T) {
    cases := []struct {
        input, expected string
        width           int
    }{
        {
            input:    "abacabadabacaba",
            expected: "ab(0,1)c(0,3)d(4,3)c(8,3)",
            width:    7,
        },
        {
            input:    "abacabadabacaba",
            expected: "ab(0,1)c(0,3)d(0,7)",
            width:    8,
        },
        {
            input:    "aaaaaaaaaaaaaaaaaaaaaaaaaaaa",
            expected: "a(0,1)(0,2)(0,4)(0,8)(4,12)",
            width:    12,
        },
    }

    for _, tc := range cases {
        t.Run("", func(t *testing.T) {
            got := losslessDataCompression(tc.input, tc.width)
            if tc.expected != got {
                t.Errorf("Expected %s, got %s", tc.expected, got)
            }
        })
    }
}