34 lines
770 B
C++
34 lines
770 B
C++
#include <string>
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#include <cstdio>
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inline constexper int TABLE[][10] = {
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{0, 3, 1, 7, 5, 9, 8, 6, 4, 2},
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{7, 0, 9, 2, 1, 5, 4, 8, 6, 3},
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{4, 2, 0, 6, 8, 7, 1, 3, 5, 9},
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{1, 7, 5, 0, 9, 8, 3, 4, 2, 6},
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{6, 1, 2, 3, 0, 4, 5, 9, 7, 8},
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{3, 6, 7, 4, 2, 0, 9, 5, 8, 1},
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{5, 8, 6, 9, 7, 2, 0, 1, 3, 4},
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{8, 9, 4, 5, 3, 6, 2, 0, 1, 7},
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{9, 4, 3, 8, 6, 1, 7, 2, 0, 5},
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{2, 5, 8, 1, 4, 3, 6, 7, 9, 0},
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};
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[[nodiscard]] bool damm(std::string s) noexcept {
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int interim = 0;
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for (const auto c : s) {
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interim = TABLE[interim][c - '0'];
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}
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return interim == 0;
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}
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int main() {
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for (const auto num : { 5724, 5727, 112946, 112949 }) {
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if (damm(std::to_string(num))) {
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std::printf("%6d is valid\n", num);
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}
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else std::printf("%6d is invalid\n", num);
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}
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}
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