Add stack-queue module: ten stack and queue interview problems, monotonic stack, min stack, queue from stacks and stack from a queue, brute-force cross-checks, dry-run traces, operation counts, pitfalls (11 tests)

Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b6nxynun5JFivebVb1
2026-11-12 22:35:43 +05:30
parent c5c435ae20
commit b9aeb78b24
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+Operation counts (counted, not timed)
+=====================================
+
+nextGreater on a strictly decreasing array (the worst case for the scan-right version)
+       n scan-right compares     stack compares stack push+pop
+    1000             499500                999           1000
+   10000           49995000               9999          10000
+  100000         4999950000              99999         100000
+
+nextGreater on random values (n = 100000): every index is pushed once and popped at most once
+pushes = 100000, pops = 99985, comparisons = 199977  (bound: comparisons <= 2n = 200000)
+
+QueueViaStacks: n enqueues followed by n dequeues
+       n    total element moves moves in the 1st dequeue
+    1000                   1000                     1000
+   10000                  10000                    10000
+  100000                 100000                   100000
+one dequeue can cost n moves, but each element moves exactly once, so n enqueues + n dequeues cost 3n steps in all
+
+StackViaQueue: n pushes
+       n      total rotations       n(n-1)/2
+     100                 4950           4950
+    1000               499500         499500
+    5000             12497500       12497500