Find the Highest Altitude
Description
There is a biker going on a road trip. The road trip consists of n + 1 points at different altitudes. The biker starts his trip on point 0 with altitude equal 0. You are given an integer array gain of length n where gain[i] is the net gain in altitude between points i and i + 1 for all (0 <= i < n). Return the highest altitude of a point.
Example 1:
Input: gain = [-5, 1, 5, 0, -7]
Output: 1
Explanation: The altitudes are [0, -5, -4, 1, 1, -6]. The highest is 1.
Example 2:
Input: gain = [-4, -3, -2, -1, 4, 3, 2]
Output: 0
Explanation: The altitudes are [0, -4, -7, -9, -10, -6, -3, -1]. The highest is 0 (the starting point).
Constraints
n == gain.length1 <= n <= 100-100 <= gain[i] <= 100
Complexity
Show Complexity
- Time:
O(n) - Space:
O(1)
Hints
Show Hints
- Pattern
- Prefix sum / Running sum
- Approach
- Start at altitude 0. Add each gain to current altitude. Track the maximum altitude seen (including the starting 0).
- Complexity
- Track running altitude and max altitude in single pass
Solutions
Show PY Solution
def solution(gain):
highest = 0
curr = 0
for i in range(len(gain)):
# alt[0] = 0
# alt[1] = gains[1] - alt[0]
# alt[2] = gain[2] - alt[1]
# ...
alt = gain[i] + curr
highest = max(highest, alt)
curr = alt
return highest