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Why is this code giving TLE?
By nipungupta37, history, 5 years ago, In English

https://mirror.codeforces.com/contest/1251/submission/76981021 can someone tell why this code is giving TLE? the complexity seems fine to me?

question link... https://mirror.codeforces.com/problemset/problem/1251/C

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5 years ago, # |
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Auto comment: topic has been updated by nipungupta37 (previous revision, new revision, compare).

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    5 years ago, # ^ |
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    Because you worst case time complexity is O(n^2).

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      5 years ago, # ^ |
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      isnt it O(10*n)?

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        5 years ago, # ^ |
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        Look at this line from your code (there are 3 such lines): 

        s3 = s3 + s[j];

        At worst, this is executed $$$n$$$ times per iteration of the outer loop. Each time, the program creates the concatenation of s3 and s[j], which could take $$$O(n)$$$ time, then assigns this concatenation to s3, which takes another $$$O(n)$$$ time to delete the old version of s3 and assign the new string. To fix this, you would want to do s3 += s[j], which doesn't re-create the string every time, or even better: s3.push_back(s[j]), which is faster performance-wise.

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