88 lines
2.2 KiB
C++
88 lines
2.2 KiB
C++
#include <algorithm>
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#include <iostream>
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#include <string>
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#include <utility>
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#include <vector>
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class SolutionConstruct {
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private:
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static inline std::string toStr(int n) {
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int i = 31;
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for (; i >= 0 && !(n & (1 << i)); --i);
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std::string ret(i + 1, '0');
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for (int j = i; j >= 0; --j)
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if (n & (1 << j))
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ret[i - j] = '1';
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return ret.empty() ? "0" : ret;
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}
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static inline int toInt(const std::string& s) {
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auto ret = 0, i = 1;
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for (auto it = s.rbegin(); it != s.rend(); ++it) {
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ret |= (*it & 1) ? i : 0;
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i <<= 1;
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}
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return ret;
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}
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static constexpr inline int eval(int n) { return (n & 0x55555555) - (n & 0xAAAAAAAA); }
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static const inline std::string L5[] = {"0", "1", "110", "111", "100", "101"};
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static const inline std::string v[] = {"01", "00", "11", "10"};
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public:
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static std::string baseNeg2(int n) {
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if (n <= 5)
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return L5[n];
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int cur, prev = 5, i = 4;
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for (; n > (cur = prev + (1 << i)); (prev = cur), (i += 2));
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auto ret = std::string(1, '0' | (n & 1));
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for (int x = (n - prev - 1) >> 1, j = 1; j < (i >> 1); (x >>= 2), ++j)
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ret = v[x & 3] + ret;
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return v[(n - prev > (cur - prev) / 2) + 2] + ret;
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}
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static void test(int n) {
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for (int i = 0; i < n; ++i) {
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int x = eval(i);
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if (x < 0)
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continue;
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if (i != toInt(baseNeg2(x)))
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std::printf("%d Bad!!\n", x);
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}
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}
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};
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/**
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* 1017. Convert to Base -2
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*
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* Given an integer n, return a binary string representing its representation in base -2.
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* Note that the returned string should not have leading zeros unless the string is "0".
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*/
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class Solution {
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private:
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static const inline std::string L5[] = {"0", "1", "110", "111", "100", "101"};
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static const inline std::string v[] = {"01", "00", "11", "10"};
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public:
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static std::string baseNeg2(int n) {
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if (n <= 5)
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return L5[n];
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int cur, prev = 5, i = 4;
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for (; n > (cur = prev + (1 << i)); (prev = cur), (i += 2));
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auto ret = std::string(1, '0' | (n & 1));
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for (int x = (n - prev - 1) >> 1, j = 1; j < (i >> 1); (x >>= 2), ++j)
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ret = v[x & 3] + ret;
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return v[(n - prev > (cur - prev) / 2) + 2] + ret;
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}
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};
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int main() {
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SolutionConstruct::test(0x1000000);
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// std::cout << Solution::baseNeg2(77);
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return 0;
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}
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