giles
97a8c06690
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Test, Build, and Deploy / test-build-deploy (push) Failing after 51s
is_balanced walks a string; on each char:
'(', '[', '{' -> Stack.push c
')', ']', '}' -> require stack non-empty AND top = expected opener,
else mark ok = false
others -> skip
At end: !ok && Stack.is_empty stack.
Five test cases:
'({[abc]d}e)' -> true
'(a]' -> false (no matching opener)
'{[}]' -> false (mismatched closer)
'(())' -> true
'' -> true
Sum of (if balanced then 1 else 0) -> 3.
Exercises:
Stack.create / push / pop / is_empty
s.[!i] string indexing
while loop + bool ref short-circuit
multi-arm if/else if/else if dispatch
31 baseline programs total.
26 lines
800 B
OCaml
26 lines
800 B
OCaml
let is_balanced s =
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let stack = Stack.create () in
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let n = String.length s in
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let ok = ref true in
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let i = ref 0 in
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while !i < n && !ok do
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let c = s.[!i] in
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(if c = '(' || c = '[' || c = '{' then Stack.push c stack
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else if c = ')' then
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(if Stack.is_empty stack || Stack.pop stack <> '(' then ok := false)
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else if c = ']' then
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(if Stack.is_empty stack || Stack.pop stack <> '[' then ok := false)
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else if c = '}' then
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(if Stack.is_empty stack || Stack.pop stack <> '{' then ok := false));
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i := !i + 1
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done;
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!ok && Stack.is_empty stack
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;;
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(if is_balanced "({[abc]d}e)" then 1 else 0) +
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(if is_balanced "(a]" then 1 else 0) +
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(if is_balanced "{[}]" then 1 else 0) +
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(if is_balanced "(())" then 1 else 0) +
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(if is_balanced "" then 1 else 0)
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