45 lines
881 B
C++
45 lines
881 B
C++
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#include <algorithm>
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#include <limits>
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#include <set>
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#include <stdexcept>
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#include <string>
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using std::set;
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using std::string;
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using std::ranges::next_permutation;
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using std::ranges::reverse;
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using std::ranges::sort;
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class Solution {
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public:
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string smallestPalindrome(string s, int k) {
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string half = s.substr(0, s.size() / 2);
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sort(half);
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set<string> permutations;
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do {
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permutations.insert(half);
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} while (next_permutation(half).found);
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if (permutations.size() > std::numeric_limits<int>::max()) {
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throw std::overflow_error("Number of permutations exceeds int limit");
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}
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int size = static_cast<int>(permutations.size());
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if (k > size) {
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return string();
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}
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auto it = permutations.begin();
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advance(it, k);
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string mirroredHalf = *it;
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reverse(mirroredHalf);
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return *it + mirroredHalf;
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}
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};
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