You are given N. Find number of pairs of integers x, y such that↵
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1 <= x < y <= N and sumOfDigits(x) > sumOfDigits(y) ↵
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Constraints:↵
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N <= 10^100 and is given as a string.↵
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Output answer modulo 1e9+7↵
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I don't remember the sign of inequality properly, it might be sumOfDigits(x) < sumOfDigits(y). I read about digit DP to solve this but I cannot find any approach. ↵
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How to solve this?
↵
1 <= x < y <= N and sumOfDigits(x) > sumOfDigits(y) ↵
↵
Constraints:↵
↵
N <= 10^100 and is given as a string.↵
↵
Output answer modulo 1e9+7↵
↵
↵
I don't remember the sign of inequality properly, it might be sumOfDigits(x) < sumOfDigits(y). I read about digit DP to solve this but I cannot find any approach. ↵
↵
How to solve this?