Count the number of times graph crosses X-axis

To find the number of times a graph crosses the X-axis, the task involves calculating the cumulative sum of an array where positive values indicate upward movement and negative values indicate downward movement. Starting from the origin, the crossing count is incremented whenever there is a transition from a negative to a non-negative cumulative sum or from a positive to a non-positive cumulative sum. This approach efficiently tracks changes in the graph's position relative to the X-axis.

The algorithm iterates through the array while maintaining a running cumulative sum. For each element, the current level is updated, and the crossing condition is checked by comparing the previous and current levels. If the graph transitions across the X-axis, the crossing count is incremented. This method ensures an O(n) time complexity and uses O(1) auxiliary space.

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