Longest substrings without repeating characters: Difference between revisions

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 a		> [a]
 </pre>
+=={{header|BCPL}}==
+<lang bcpl>get "libhdr"
+// Fills up 'v' with words where w%0 is the start and w%1 is the end
+// of each longest substring
+let lswrc(s, v) = valof
+$(  let seen = vec 255
+    let start = 1 and i = 1 and maxStart = 1 and maxEnd = 1 and n = 0
+    for i=0 to 255 do i!seen := false
+    while i <= s%0
+    $(  test (s%i)!seen
+            while (s%i)!seen
+            $(  (s%start)!seen := false
+                start := start + 1
+            $)
+        or
+        $(  (s%i)!seen := true
+            if i - start >= maxEnd - maxStart
+            $(  maxStart := start
+                maxEnd := i
+                while n>0 & (v+n-1)%1 - (v+n-1)%0 < i-start
+                    do n := n-1
+                (v+n)%0 := start
+                (v+n)%1 := i
+                n := n+1
+            $)
+            i := i + 1
+        $)
+    $)
+    resultis n
+$)
+let substr(s, start, end, buf) = valof
+$(  buf%0 := end - start + 1
+    for i = start to end do
+        buf%(i-start+1) := s%i
+    resultis buf
+$)
+let example(s) be
+$(  let v = vec 32 and b = vec 32
+    let n = lswrc(s, v)
+    writef("Original string: '%s'*N", s)
+    writes("Longest substrings: ")
+    test n=0 do
+        writes("<empty>")
+    or for i = 0 to n-1 do
+        writef("'%s' ", substr(s, (v+i)%0, (v+i)%1, b))
+    wrch('*N')
+$)
+let start() be
+$(  example("xyzyabcybdfd")
+    example("xyzyab")
+    example("zzzzz")
+    example("a")
+    example("")
+$)</lang>
+{{out}}
+<pre>Original string: 'xyzyabcybdfd'
+Longest substrings: 'zyabc' 'cybdf'
+Original string: 'xyzyab'
+Longest substrings: 'zyab'
+Original string: 'zzzzz'
+Longest substrings: 'z' 'z' 'z' 'z' 'z'
+Original string: 'a'
+Longest substrings: 'a'
+Original string: ''
+Longest substrings: <empty></pre>
 =={{header|C++}}==