DSA · interactive
Monotonic stack: days until a warmer day
For each day, how long until it gets warmer? Checking forward from every day is O(n²). Keep a stack of days still waiting, coldest on top, and each day is pushed and popped at most once.
73°d0·
74°d1·
75°d2·
71°d3·
69°d4·
72°d5·
76°d6·
73°d7·
Stackbottom
- empty
Empty stack. Each day waits on the stack until a warmer day shows up.
0 stack operations · max 16
1 Walk the days left to right, once.
—
2 3 4
Now solve it
In production
Tools and technologies
“Next greater element” questions show up in stock spans, histograms and skyline problems.
Not tied to one language — use these names when you search docs or design a system.