On 13th June there was Codeforces round #649. In problem D during the round, there were only 137 test cases as the main test, so lot of people got AC during the round but afterward, the number of test cases was increased to 142 and many passed solutions were failing in those test cases. and this is not the first time this happened, In Codeforces Round #637 (Div. 2), problem D had only 24 test cases initially which allowed even greedy solutions to GET AC, which was failing in afterward added test cases. So is there any reason for this happening and will it be solved?↵
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Solution That got AC during round But Failed when new test Cases were added:-↵
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1. [Codeforces round #649 D](https://codeforces.net/contest/1364/submission/83700045)↵
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2.[Codeforces Round #637 (Div. 2) D](https://codeforces.net/contest/1341/submission/83700765)↵
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(P.S.:- These solutions got AC even after the system test as at that time there were fewer test cases but Now if you submit them, they won't pass as test cases got increased)
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Solution That got AC during round But Failed when new test Cases were added:-↵
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1. [Codeforces round #649 D](https://codeforces.net/contest/1364/submission/83700045)↵
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2.[Codeforces Round #637 (Div. 2) D](https://codeforces.net/contest/1341/submission/83700765)↵
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(P.S.:- These solutions got AC even after the system test as at that time there were fewer test cases but Now if you submit them, they won't pass as test cases got increased)