Nested Loop Python

Question

count = 1
for i in range(10):
    for j in range(0, i):
        print(count, end=\'\')
        count = count +1
    print()
input()

I am writing a

Answer 1

Others have suggested some interesting solutions but this can also be done mathematically using a simple observation. Notice that:

1 - 1*1

22 - 2*11

333 - 3*111

4444 - 4*1111

and so on ....

We can have a general formula for producing 1,11,111,1111,... at every iteration. Observe that:

1 = 9/9 = (10 - 1)/9 = (10^1 - 1)/9

11 = 99/9 = (100 - 1)/9 = (10^2 - 1)/9

111 = 999/9 = (1000 - 1)/9 = (10^3 - 1)/9

......

that is we have (10^i - 1)/9 for the ith iteration.

Now it is simple enough to implement. We will multiply i with the above formula in each iteration. Hence the overall formula is:

i*(10^i - 1)/9 (for every ith iteration). Here's the python code:

for i in xrange(1,10):
    print i*(10**i-1)/9

Hope this helps.