How should I practice Count Visible People to the Left?

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Count Visible People to the Left

Google● HardINTERNFULLTIMEPHONE SCREENONSITE INTERVIEW

Problem statement

There are n people standing in a line, indexed from left to right. Every person faces left, and heights[i] is person i's height. All heights are distinct.

Person i can see person j to the left, where j < i, exactly when no person k between them is taller than both endpoints. In other words, there must be no k with j < k < i and heights[k] > max(heights[i], heights[j]).

The problem statement continues

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Examples

Example 1

heights = [1,10,6,7,9,8,2,4,3,5]return = [0,1,1,2,3,2,3,4,4,6]

The warm-up asks only about the last person, whose height is 5. Looking left, that person can see heights 3, 4, 2, 8, 9, and 10, so the last count is 6. Height 9 blocks heights 7 and 6, while height 10 blocks height 1. Applying the same rule to every position gives the returned array.

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