Python 在嵌套 for 循环中编写嵌套 if-else 的有效方法

Question

I'm working on a code challenge in which I have to reduce the execution time as much as possible, the only thing I able to find where I can make an improvement is a nested if-else statement inside a nested for-loop but I'm not sure how it can be improvided.

Here's my code:

mat = [[0] * n] * n
count = 0
for i in range(n,0,-1):
    count += 1
    for j in range(i,n+1,1):
        if i == j:
            pass
        else:
            if getEnemyStatus(mat, i, j):
               break
            else:
                if isEnemy(enemyDict, i, j):
                    setStatus(mat, i, j)
                    break
                else:
                    count += 1

value of n can be from 1 to 10^5

Answer 1

You can skip the first if condition by starting with i+1 in range

for j in range(i+1, n+1, 1):
   # code here

Second, nested if else condition should be avoided with elif for reading purpose.

Update code should be like:

mat = [[0] * n] * n
count = 0
for i in range(n,0,-1):
    count += 1
    for j in range(i + 1, n + 1, 1):
        if getEnemyStatus(mat, i, j):
            break
        elif isEnemy(enemyDict, i, j):
            setStatus(mat, i, j)
            break
        else:
            count += 1

NOTE : Also if you can set the status setStatus in your isEnemy function then you can get more cleaner code:

mat = [[0] * n] * n
count = 0
for i in range(n,0,-1):
    count += 1
    for j in range(i + 1, n + 1, 1):
        if getEnemyStatus(mat, i, j) or isEnemy(enemyDict, i, j):
            break
        count += 1