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Paint House

Dynamic Programming·Medium

There are n houses in a row. Each house can be painted one of 3 colors: red, blue, or green. The cost of painting house i with color j is costs[i][j].

Adjacent houses cannot have the same color. Return the minimum total painting cost.

DP recurrence: for each house i and color j, the minimum cost is costs[i][j] + min(costs[i-1][other colors]).

Examples

Input: costs = [[17,2,17],[16,16,5],[14,3,19]]

Output: 10

Paint house 0 blue (2), house 1 green (5), house 2 blue (3). Total = 10.

Input: costs = [[7,6,2]]

Output: 2

Constraints

costs.length == n
costs[i].length == 3
1 <= n <= 100
1 <= costs[i][j] <= 20

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First attempt — retry to track metric movement here.

Your approach

Pattern:Dynamic Programming
Time:O(N)
Space:O(1)

Complete approach — pattern and complexity both named.

Coach

What you got right

You correctly matched the sorted input requirement and implemented a linear-time scan using two pointers.

Where it diverged

No divergence detected. The code correctly aligns with the stated approach.

Next attempt: focus on

Try solving related sliding window problems to build familiarity with two-pointer variants.

Signals

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