Facing the sun

JavaView on GFG

Time: O(n)

Space: O(1)

Problem Overview

Count buildings that can see the sunrise (no taller building to the left).

Intuition

Count buildings that can see the sunrise (no taller building to the left). Scan left to right tracking max height.

Algorithm

1maxH = 0. For each building: if height > maxH: count++, maxH = height.

Common Pitfalls

• First building always sees sun. Each subsequent: sees sun only if taller than all previous. O(n).

Facing the sun.java

Java

// Approach: Greedy. A building faces sun if it is taller than all buildings to its left.
// Track the current maximum height from the left.
// Time: O(n) Space: O(1)
class Solution {
    // Returns count buildings that can see sunlight
    public int countBuildings(int[] height) {
        int maxi = height[0];
        int cnt = 1;

        for (int i = 1; i < height.length; i++) {
            if (height[i] > maxi) {
                maxi = height[i];
                cnt++;
            }

        }
        return cnt;
    }
}

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