adding knapsack (#151)

config.json

@@ -369,6 +369,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "knapsack",
+        "name": "Knapsack",
+        "uuid": "0408328a-3e04-4e2a-b5bf-fad131747a09",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "meetup",
         "name": "Meetup",

exercises/practice/knapsack/.docs/instructions.md

@@ -0,0 +1,37 @@
+# Instructions
+
+In this exercise, let's try to solve a classic problem.
+
+Bob is a thief. After months of careful planning, he finally manages to
+crack the security systems of a high-class apartment.
+
+In front of him are many items, each with a value (v) and weight (w). Bob,
+of course, wants to maximize the total value he can get; he would gladly
+take all of the items if he could. However, to his horror, he realizes that
+the knapsack he carries with him can only hold so much weight (W).
+
+Given a knapsack with a specific carrying capacity (W), help Bob determine
+the maximum value he can get from the items in the house. Note that Bob can
+take only one of each item.
+
+All values given will be strictly positive. Items will be represented as a
+list of pairs, `wi` and `vi`, where the first element `wi` is the weight of
+the *i*th item and `vi` is the value for that item.
+
+For example:
+
+Items: [
+  { "weight": 5, "value": 10 },
+  { "weight": 4, "value": 40 },
+  { "weight": 6, "value": 30 },
+  { "weight": 4, "value": 50 }
+]
+
+Knapsack Limit: 10
+
+For the above, the first item has weight 5 and value 10, the second item has
+weight 4 and value 40, and so on.
+
+In this example, Bob should take the second and fourth item to maximize his
+value, which, in this case, is 90. He cannot get more than 90 as his
+knapsack has a weight limit of 10.

exercises/practice/knapsack/.meta/config.json

@@ -0,0 +1,26 @@
+{
+  "authors": [
+    "kapitaali"
+  ],
+  "files": {
+    "solution": [
+      "src/knapsack.cob"
+    ],
+    "test": [
+      "tst/knapsack/knapsack.cut"
+    ],
+    "example": [
+      ".meta/proof.ci.cob"
+    ],
+    "invalidator": [
+      "test.ps1",
+      "test.sh",
+      "bin/fetch-cobolcheck",
+      "bin/fetch-cobolcheck.ps1",
+      "config.properties"
+    ]
+  },
+  "blurb": "Given a knapsack that can only carry a certain weight, determine which items to put in the knapsack in order to maximize their combined value.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Knapsack_problem"
+}

exercises/practice/knapsack/.meta/proof.ci.cob

@@ -0,0 +1,85 @@
+       IDENTIFICATION DIVISION.
+       PROGRAM-ID. KNAPSACK.
+       AUTHOR. kapitaali.
+       ENVIRONMENT DIVISION.
+       CONFIGURATION SECTION.
+       REPOSITORY.
+           FUNCTION ALL INTRINSIC.
+
+       DATA DIVISION.
+       WORKING-STORAGE SECTION.
+       01 WS-INPUTS.
+           05 MAXIMUM-WEIGHT    PIC 999.
+           05 NO-OF-ITEMS       PIC 99.
+
+       01 KNAPSACKTABLE.
+           05 TABLEROW          OCCURS 1 TO 20 DEPENDING ON NO-OF-ITEMS
+                                   INDEXED BY INDX.
+              10 WS-WEIGHT      PIC 9999.
+              10 WS-VALUE       PIC 9999.
+
+       01 WS-OUTPUTS.
+           05 WS-RESULT         PIC 9999.
+
+       01 MY-VARS.
+           05 A                 PIC 9999.
+           05 B                 PIC 9999.
+           05 C                 PIC 9999.
+           05 I                 PIC 9999.
+           05 J                 PIC 9999.
+           05 ITEMS-PLUS1       PIC 9999.
+           05 WEIGHT-PLUS1      PIC 9999.
+
+       01 MY-TABLE.
+           05 W           OCCURS 1 TO 9999 DEPENDING ON MAXIMUM-WEIGHT.
+              10 ITEMS    OCCURS 20 TIMES.
+                 15 M     PIC 9999.
+
+
+       PROCEDURE DIVISION.
+
+
+       INIT-MY-TABLE.
+           IF MAXIMUM-WEIGHT = 0
+              MOVE 1 TO MAXIMUM-WEIGHT 
+              INITIALIZE MY-TABLE
+              MOVE 0 TO MAXIMUM-WEIGHT 
+           ELSE
+              INITIALIZE MY-TABLE
+           END-IF.
+
+
+       MAXIMUM-VALUE.  
+           PERFORM INIT-MY-TABLE.
+           MOVE ZEROES TO MY-TABLE.
+           MOVE ZEROES TO MY-VARS.
+           INITIALIZE WS-RESULT.
+           SET INDX TO NO-OF-ITEMS.
+           IF NO-OF-ITEMS = 1
+              IF WS-WEIGHT(1) > MAXIMUM-WEIGHT 
+                 EXIT PROGRAM 
+              END-IF
+           END-IF.
+           SORT TABLEROW DESCENDING WS-VALUE WS-WEIGHT.
+           PERFORM VARYING I FROM 1 BY 1 UNTIL I > NO-OF-ITEMS 
+              PERFORM VARYING J FROM 1 BY 1 UNTIL J > MAXIMUM-WEIGHT    
+                 IF WS-WEIGHT(I) > J THEN
+                    COMPUTE C = I - 1
+                    IF C = 0
+                       MOVE 0 TO M(J,I)
+                    ELSE
+                       MOVE M(J, C) TO M(J,I) 
+                    END-IF
+                 ELSE
+                    COMPUTE B = J - WS-WEIGHT(I)
+                    IF C > 0 AND B > 0
+                       COMPUTE A = WS-VALUE(I) + M(B, C)
+                       COMPUTE M(J,I) = MAX(M(J, C), A)
+                    ELSE
+                       COMPUTE A = WS-VALUE(I) 
+                       COMPUTE M(J,I) = MAX(0, A)
+                    END-IF 
+                 END-IF
+              END-PERFORM
+           END-PERFORM.
+           MOVE M(MAXIMUM-WEIGHT, NO-OF-ITEMS) TO WS-RESULT.

exercises/practice/knapsack/bin/fetch-cobolcheck

@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+
+# This file is a copy of the
+# https://github.com/exercism/configlet/blob/main/scripts/fetch-configlet file.
+# Please submit bugfixes/improvements to the above file to ensure that all tracks benefit from the changes.
+
+# set -eo pipefail
+
+readonly LATEST='https://api.github.com/repos/0xE282B0/cobol-check/releases/latest'
+
+case "$(uname)" in
+  Darwin*)   os='mac'     ;;
+  Linux*)    os='linux'   ;;
+  Windows*)  os='windows' ;;
+  MINGW*)    os='windows' ;;
+  MSYS_NT-*) os='windows' ;;
+  *)         os='linux'   ;;
+esac
+
+case "${os}" in
+  windows*) ext='.exe' ;;
+  *)        ext='' ;;
+esac
+
+arch="$(uname -m)"
+
+curlopts=(
+  --silent
+  --show-error
+  --fail
+  --location
+  --retry 3
+)
+
+if [[ -n "${GITHUB_TOKEN}" ]]; then
+  curlopts+=(--header "authorization: Bearer ${GITHUB_TOKEN}")
+fi
+
+suffix="${os}-${arch}${ext}"
+
+get_download_url() {
+  curl "${curlopts[@]}" --header 'Accept: application/vnd.github.v3+json' "${LATEST}" |
+    grep "\"browser_download_url\": \".*/download/.*/cobol-check.*${suffix}\"$" |
+    cut -d'"' -f4
+}
+
+main() {
+  if [[ -d ./bin ]]; then
+    output_dir="./bin"
+  elif [[ $PWD == */bin ]]; then
+    output_dir="$PWD"
+  else
+    echo "Error: no ./bin directory found. This script should be ran from a repo root." >&2
+    return 1
+  fi
+
+  output_path="${output_dir}/cobolcheck${ext}"
+  download_url="$(get_download_url)"
+  curl "${curlopts[@]}" --output "${output_path}" "${download_url}"
+  chmod +x "${output_path}"
+}
+
+main

exercises/practice/knapsack/bin/fetch-cobolcheck.ps1

@@ -0,0 +1,28 @@
+# This file is a copy of the
+# https://github.com/exercism/configlet/blob/main/scripts/fetch-configlet.ps1 file.
+# Please submit bugfixes/improvements to the above file to ensure that all tracks
+# benefit from the changes.
+
+$ErrorActionPreference = "Stop"
+$ProgressPreference = "SilentlyContinue"
+
+$requestOpts = @{
+    Headers           = If ($env:GITHUB_TOKEN) { @{ Authorization = "Bearer ${env:GITHUB_TOKEN}" } } Else { @{ } }
+    MaximumRetryCount = 3
+    RetryIntervalSec  = 1
+}
+
+$arch = If ([Environment]::Is64BitOperatingSystem) { "amd64" } Else { "x86" }
+$fileName = "cobol-check-windows-$arch.exe"
+
+Function Get-DownloadUrl {
+    $latestUrl = "https://api.github.com/repos/0xE282B0/cobol-check/releases/latest"
+    Invoke-RestMethod -Uri $latestUrl -PreserveAuthorizationOnRedirect @requestOpts
+    | Select-Object -ExpandProperty assets
+    | Where-Object { $_.browser_download_url -match $FileName }
+    | Select-Object -ExpandProperty browser_download_url
+}
+
+$downloadUrl = Get-DownloadUrl
+$outputFile = Join-Path -Path $PSScriptRoot -ChildPath "cobolcheck.exe"
+Invoke-WebRequest -Uri $downloadUrl -OutFile $outputFile @requestOpts