Buggy python submission (verdict: Runtime Error):
for p in P:
    # 期待値
    # 累積和
    exp += (1+p)/2
    p_e.append(exp)  
if n == k:
    print(p_e[-1])
else:
    # 初期値
    maxv = p_e[k-1] - 0
    for i in range(1, n-k):
        # 隣接するk個の期待値の和
        p_sum = p_e[k+i] - p_e[i]
        maxv = max(maxv, p_sum)
    print(maxv)

Fixed submission:
def main():
    n, k = map(int, input().split())
    P = [int(x) for x in input().split()]
    p_e = list()
    exp = 0
    for p in P:
        # 期待値
        # 累積和
        exp += (1+p)/2
        p_e.append(exp)  
    if n == k:
        print(p_e[-1])
    else:
        # 初期値
        maxv = p_e[k-1] - p_e[0]
        for i in range(1, n-k):
            # 隣接するk個の期待値の和
            p_sum = p_e[k+i] - p_e[i]
            maxv = max(maxv, p_sum)
        print(maxv)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
def main():
    n, k = map(int, input().split())
    P = [int(x) for x in input().split()]
    exp = list()
    for p in P:
        # 期待値
        exp.append((1+p)/2)
    p_e = list()
    e_cum = 0
    for i in exp:
        # 累積和
        e_cum += i
        p_e.append(e_cum)
    # maxv = 0
    maxv = p_e[k] - p_e[0]
    for i in range(1, n-k):
        # 隣接するk個の期待値の和
        p_sum = p_e[k+i] - p_e[i]
        maxv = max(maxv, p_sum)
    print(maxv)

if __name__ == '__main__':
    main()
    

Fixed submission:
def main():
    n, k = map(int, input().split())
    P = [int(x) for x in input().split()]
    p_e = list()
    exp = 0
    for p in P:
        # 期待値
        # 累積和
        exp += (1+p)/2
        p_e.append(exp)  
    if n == k:
        print(p_e[-1])
    else:
        # 初期値
        maxv = p_e[k-1] - p_e[0]
        for i in range(1, n-k):
            # 隣接するk個の期待値の和
            p_sum = p_e[k+i] - p_e[i]
            maxv = max(maxv, p_sum)
        print(maxv)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
def main():
    n, k = map(int, input().split())
    P = [int(x) for x in input().split()]
    p_e = list()
    exp = 0
    for p in P:
        # 期待値
        # 累積和
        exp += (1+p)/2
        p_e.append(exp)
    maxv = p_e[k] - p_e[0]
    for i in range(1, n-k):
        # 隣接するk個の期待値の和
        p_sum = p_e[k+i] - p_e[i]
        maxv = max(maxv, p_sum)
    print(maxv)

if __name__ == '__main__':
    main()
    

Fixed submission:
def main():
    n, k = map(int, input().split())
    P = [int(x) for x in input().split()]
    p_e = list()
    exp = 0
    for p in P:
        # 期待値
        # 累積和
        exp += (1+p)/2
        p_e.append(exp)  
    if n == k:
        print(p_e[-1])
    else:
        # 初期値
        maxv = p_e[k-1] - p_e[0]
        for i in range(1, n-k):
            # 隣接するk個の期待値の和
            p_sum = p_e[k+i] - p_e[i]
            maxv = max(maxv, p_sum)
        print(maxv)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
def main():
    n, k = map(int, input().split())
    p = [int(x) for x in input().split()]
    maxv = 0
    for i in range(n-k+1):
        maxv = max(maxv, (sum(p[i:i+k])+k)/2)
    print(maxv)

if __name__ == '__main__':
    main()
    

Fixed submission:
def main():
    n, k = map(int, input().split())
    P = [int(x) for x in input().split()]
    p_e = list()
    exp = 0
    for p in P:
        # 期待値
        # 累積和
        exp += (1+p)/2
        p_e.append(exp)  
    if n == k:
        print(p_e[-1])
    else:
        # 初期値
        maxv = p_e[k-1] - p_e[0]
        for i in range(1, n-k):
            # 隣接するk個の期待値の和
            p_sum = p_e[k+i] - p_e[i]
            maxv = max(maxv, p_sum)
        print(maxv)

if __name__ == '__main__':
    main()