adding binary-search

config.json

@@ -313,6 +313,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "binary-search",
+        "name": "Binary Search",
+        "uuid": "4a580b6d-a370-4526-a5ea-d7c856279676",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "pascals-triangle",
         "name": "Pascal's Triangle",

exercises/practice/binary-search/.docs/instructions.md

@@ -0,0 +1,36 @@
+# Instructions
+
+Implement a binary search algorithm. Do not use any COBOL proprietary
+search routines (eg. SEARCH).
+
+Searching a sorted collection is a common task. A dictionary is a sorted
+list of word definitions. Given a word, one can find its definition. A
+telephone book is a sorted list of people's names, addresses, and
+telephone numbers. Knowing someone's name allows one to quickly find
+their telephone number and address.
+
+If the list to be searched contains more than a few items (a dozen, say)
+a binary search will require far fewer comparisons than a linear search,
+but it imposes the requirement that the list be sorted.
+
+In computer science, a binary search or half-interval search algorithm
+finds the position of a specified input value (the search "key") within
+an array sorted by key value.
+
+In each step, the algorithm compares the search key value with the key
+value of the middle element of the array.
+
+If the keys match, then a matching element has been found and its index,
+or position, is returned.
+
+Otherwise, if the search key is less than the middle element's key, then
+the algorithm repeats its action on the sub-array to the left of the
+middle element or, if the search key is greater, on the sub-array to the
+right.
+
+If the remaining array to be searched is empty, then the key cannot be
+found in the array and a special "not found" indication is returned.
+
+A binary search halves the number of items to check with each iteration,
+so locating an item (or determining its absence) takes logarithmic time.
+A binary search is a dichotomic divide and conquer search algorithm.

exercises/practice/binary-search/.docs/introduction.md

@@ -0,0 +1,35 @@
+# Introduction
+
+Implement a binary search algorithm.
+
+Searching a sorted collection is a common task. A dictionary is a sorted
+list of word definitions. Given a word, one can find its definition. A
+telephone book is a sorted list of people's names, addresses, and
+telephone numbers. Knowing someone's name allows one to quickly find
+their telephone number and address.
+
+If the list to be searched contains more than a few items (a dozen, say)
+a binary search will require far fewer comparisons than a linear search,
+but it imposes the requirement that the list be sorted.
+
+In computer science, a binary search or half-interval search algorithm
+finds the position of a specified input value (the search "key") within
+an array sorted by key value.
+
+In each step, the algorithm compares the search key value with the key
+value of the middle element of the array.
+
+If the keys match, then a matching element has been found and its index,
+or position, is returned.
+
+Otherwise, if the search key is less than the middle element's key, then
+the algorithm repeats its action on the sub-array to the left of the
+middle element or, if the search key is greater, on the sub-array to the
+right.
+
+If the remaining array to be searched is empty, then the key cannot be
+found in the array and a special "not found" indication is returned.
+
+A binary search halves the number of items to check with each iteration,
+so locating an item (or determining its absence) takes logarithmic time.
+A binary search is a dichotomic divide and conquer search algorithm.

exercises/practice/binary-search/.meta/config.json

@@ -0,0 +1,23 @@
+{
+  "authors": [
+    "kapitaali"
+  ],
+  "files": {
+    "solution": [
+      "src/binary-search.cob"
+    ],
+    "test": [
+      "tst/binary-search/binary-search.cut"
+    ], 
+    "example": [
+      ".meta/proof.ci.cob"
+    ],
+    "invalidator": [
+      "test.sh",
+      "test.ps1"
+    ]
+  },
+  "blurb": "Implement a binary search algorithm.",
+  "source": "Wikipedia",
+  "source_url": "http://en.wikipedia.org/wiki/Binary_search_algorithm"
+}

exercises/practice/binary-search/.meta/proof.ci.cob

@@ -0,0 +1,106 @@
+       IDENTIFICATION DIVISION.
+       PROGRAM-ID. BINARY-SEARCH.
+       AUTHOR. kapitaali.
+       ENVIRONMENT DIVISION.
+       DATA DIVISION.
+       WORKING-STORAGE SECTION.
+       01 WS-ITEM                  PIC 9999.
+       01 WS-RESULT                PIC 9999.
+       01 WS-ERROR                 PIC X(40) VALUE SPACES.
+       01 WS-ARRAY                 PIC X(60).
+       01 L                        PIC 99 VALUE 0.
+       01 R                        PIC 99.
+       01 M                        PIC 99.
+       01 STR                      PIC X(60).
+       01 EXP                      PIC 999 VALUE ZEROES.
+       01 IDX                      PIC 999.
+       01 NUM2                     PIC ZZ9 VALUE ZEROES.
+       01 COUNTER                  PIC 999.
+       01 LEN                      PIC 999.       
+
+       01 Teibel. 
+         02 Taulukko               PIC 999 OCCURS 1 TO 20
+                                   DEPENDING ON IDX.        
+
+       PROCEDURE DIVISION.            
+
+       STR-LENGTH.
+           MOVE 0 TO LEN.
+           PERFORM VARYING COUNTER FROM FUNCTION LENGTH(STR)
+                   BY -1 UNTIL STR(COUNTER:1) <> " "
+               ADD 1 TO LEN
+           END-PERFORM.
+           COMPUTE LEN = FUNCTION LENGTH(STR) - LEN. 
+
+
+       REVERSE-TABLE.
+           COMPUTE R = FUNCTION INTEGER-PART(IDX / 2).
+           PERFORM VARYING COUNTER FROM 1 BY 1 UNTIL COUNTER = R
+              COMPUTE L = IDX - COUNTER
+              MOVE Taulukko(L) TO NUM2
+              MOVE Taulukko(COUNTER) TO Taulukko(L)
+              MOVE NUM2 TO Taulukko(COUNTER)
+           END-PERFORM.
+
+
+      * populates the table from input string
+       MOVE-TO-TABLE.
+           MOVE WS-ARRAY TO STR.
+           PERFORM STR-LENGTH.
+           MOVE 20 TO IDX.
+           INITIALIZE Teibel.
+           MOVE 3 TO EXP. 
+           MOVE 1 TO IDX
+           MOVE ZEROES TO NUM2.
+           PERFORM VARYING COUNTER FROM LEN BY -1 UNTIL COUNTER = 0
+               IF WS-ARRAY(COUNTER:1) = ','
+                   MOVE 3 TO EXP
+                   MOVE NUM2 TO Taulukko(IDX)
+                   MOVE ZEROES TO NUM2
+                   ADD 1 TO IDX
+               ELSE IF COUNTER = 1
+                   MOVE WS-ARRAY(COUNTER:1) TO NUM2(EXP:1)
+                   MOVE NUM2 TO Taulukko(IDX)
+                   ADD 1 TO IDX
+               ELSE 
+                   MOVE WS-ARRAY(COUNTER:1) TO NUM2(EXP:1)
+                   SUBTRACT 1 FROM EXP
+               END-IF
+           END-PERFORM.
+
+      * the actual algorithm
+       BINARY-SEARCH. 
+           MOVE ZERO TO WS-RESULT.
+           MOVE SPACES TO WS-ERROR.
+           PERFORM MOVE-TO-TABLE.
+           IF IDX > 2
+              PERFORM REVERSE-TABLE  
+           END-IF.
+           IF L IS LESS THAN 1 OR R IS GREATER THAN IDX 
+              MOVE "value not in array" TO WS-ERROR 
+              EXIT PROGRAM 
+           END-IF.
+           MOVE 1 TO L. 
+           COMPUTE R = IDX - 1.
+           PERFORM UNTIL L IS GREATER THAN R
+              COMPUTE M = L + R
+              COMPUTE M = FUNCTION INTEGER-PART(M / 2)
+              IF Taulukko(M) = WS-ITEM 
+                MOVE M TO WS-RESULT 
+                EXIT PARAGRAPH
+              END-IF
+              IF Taulukko(M) IS LESS THAN WS-ITEM 
+                 COMPUTE L = M + 1
+              ELSE IF Taulukko(M) IS GREATER THAN WS-ITEM 
+                 COMPUTE R = M - 1
+              ELSE
+                 COMPUTE WS-RESULT = M - 1
+                 IF Taulukko(WS-RESULT) = WS-ITEM 
+                   EXIT PROGRAM
+                 ELSE
+                   MOVE "value not in array" TO WS-ERROR 
+                   EXIT PROGRAM  
+                 END-IF
+              END-IF
+           END-PERFORM.
+           MOVE "value not in array" TO WS-ERROR.

exercises/practice/binary-search/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/binary-search/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