Python 代码
n = int(input())
nums = [0, 0] + list(map(int, input().split()))
dp = [[-float('inf'), -float('inf')] for _ in range(n+2)]
dp[0][0] = 0
dp[1][0] = 0
for i in range(2, n+2):
dp[i][0] = max(dp[i-1][0], dp[i-1][1] + nums[i])
dp[i][1] = max(dp[i-1][1], dp[i-2][0] - nums[i])
print(dp[n+1][0])