201803-2 python CCF 更简单的思路和代码 100分

n, L, t = map(int, input().split())
ball_positions = list(map(int, input().split()))
ball_directions = [1] * n
for i in range(t):
    ball_hits = list(map(ball_positions.count, ball_positions))#统计每个位置的球的数量
    for i in range(n):
        if ball_positions[i] == L or ball_positions[i] == 0:#检查端点
            ball_directions[i] = -ball_directions[i]
        if ball_hits[i] == 2:#检查相撞
            ball_directions[i] = -ball_directions[i]
        ball_positions[i] += ball_directions[i]#小球开始运动一秒
print(" ".join(map(str, ball_positions)))

思路：模拟小球真实运动就可以了，三个list分别存放小球的当前位置，小球的当前速度（矢量），当前位置的小球数量

注意：此解法未考虑初始时刻两个小球在端点位置的情况，如若考虑的话，先判断相撞，再判断端点，且修改下面代码

if ball_positions[i] == L or ball_positions[i] == 0:#检查端点
            ball_directions[i] = -ball_directions[i]

为

if ball_positions[i] == L:#检查端点
            ball_directions[i] = -1
if ball_positions[i] == 0:#检查端点
            ball_directions[i] = 1