Recursion & DP Clean Patterns

public void dfs(TreeNode node) {
    if (node == null) {
        return;
    }
    dfs(node.left);
    dfs(node.right);
}

Base case first. Always.

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DP Pattern

Define:

• State
• Transition
• Base case

// dp[i] = maximum subarray sum ending at i
dp[i] = Math.max(numbers[i], numbers[i] + dp[i - 1]);