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Sum of Subarray Minimums — Monotonic Stack Contribution
Sum of minimums of all subarrays. For each element, count how many subarrays have it as minimum using previous/next smaller element positions.
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1276 articles
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Maximum Width Ramp — Monotonic Stack + Two Pass
Find max j-i where i<j and nums[i]<=nums[j]. Build decreasing monotonic stack for left candidates, then scan from right to match.
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132 Pattern — Monotonic Stack from Right
Find i<j<k where nums[i]<nums[k]<nums[j]. Scan right-to-left with decreasing stack; track max popped element as potential 'nums[k]' candidate.
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Maximal Rectangle — Histogram per Row
Find the largest rectangle in a binary matrix. Build histogram row by row (reset to 0 on '0'), apply Largest Rectangle in Histogram each row.
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Next Greater Element II — Circular Monotonic Stack
Next greater element in circular array. Iterate twice (2n) but use index mod n. Same decreasing stack pattern.
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