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add: 220302-CN [cpp]

This commit is contained in:
Lam Haoyin 2022-03-02 22:20:46 +08:00
parent f96d8bc6cb
commit 7c317607f4
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GPG Key ID: 8C089CB1A2B7544F
2 changed files with 105 additions and 1 deletions
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104
cpp/2203/220302-CN.cpp Normal file
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@ -0,0 +1,104 @@
#include <string>
#include <iostream>
class Solution {
private:
static inline constexpr unsigned long long diffULL(unsigned long long x, unsigned long long y) {
return std::max(x, y) - std::min(x, y);
}
static inline constexpr unsigned long long gen1001(unsigned long long n) {
int digits = 1;
for (auto i = n; i > 9; i /= 10)
++digits;
unsigned long long ret = 1;
for (int i = 0; i < digits; ++i)
ret *= 10;
return ret + 1;
}
static inline constexpr unsigned long long gen999(unsigned long long n) {
int digits = 1;
for (auto i = n; i > 9; i /= 10)
++digits;
unsigned long long ret = 1;
for (int i = 1; i < digits; ++i)
ret *= 10;
return ret - 1;
}
public:
static std::string nearestPalindromic(const std::string& n) {
auto nNum = std::stoull(n);
if (nNum <= 10)
return std::to_string(nNum - 1);
else if (nNum == 11)
return "9";
else if (nNum <= 16)
return "11";
else if (nNum <= 26)
return "22";
auto nLen = n.length();
if (nLen & 1) {
auto absMin = 0xFFFFFFFFFFFFFFFFULL;
std::string ans;
for (int i = -1; i <= 1; ++i) {
std::string prefix = n.substr(0, nLen >> 1);
std::string thisNumStr = prefix;
thisNumStr.push_back(std::isdigit(n[nLen >> 1] + i) ? (n[nLen >> 1] + i) : n[nLen >> 1]);
thisNumStr.insert(thisNumStr.end(), prefix.rbegin(), prefix.rend());
auto thisNum = std::stoull(thisNumStr);
if (thisNum == nNum)
continue;
if (diffULL(thisNum, nNum) < absMin || (diffULL(thisNum, nNum) == absMin && thisNum < std::stoull(ans))) {
absMin = diffULL(thisNum, nNum);
ans = thisNumStr;
}
}
auto retNum = std::stoull(ans);
if (!absMin || (gen1001(nNum) != nNum && (diffULL(gen1001(nNum), nNum) < absMin || (diffULL(gen1001(nNum), nNum) == absMin && gen1001(nNum) < retNum)))) {
absMin = diffULL(gen1001(nNum), nNum);
retNum = gen1001(nNum);
}
if (!absMin || (gen999(nNum) != nNum && (diffULL(gen999(nNum), nNum) < absMin || (diffULL(gen999(nNum), nNum) == absMin && gen999(nNum) < retNum)))) {
retNum = gen999(nNum);
}
return std::to_string(retNum);
} else {
auto prefixNum = std::stoull(n.substr(0, nLen >> 1)), absMin = 0xFFFFFFFFFFFFFFFFULL;
std::string ans;
for (int i = -1; i <= 1; ++i) {
auto thisPrefix = std::to_string(prefixNum + i);
auto thisNumStr = thisPrefix;
thisNumStr.insert(thisNumStr.end(), thisPrefix.rbegin(), thisPrefix.rend());
auto thisNum = std::stoull(thisNumStr);
if (thisNum == nNum)
continue;
if (diffULL(thisNum, nNum) < absMin || (diffULL(thisNum, nNum) == absMin && thisNum < std::stoull(ans))) {
absMin = diffULL(thisNum, nNum);
ans = thisNumStr;
}
}
auto retNum = std::stoull(ans);
if (!absMin || (gen1001(nNum) != nNum && (diffULL(gen1001(nNum), nNum) < absMin || (diffULL(gen1001(nNum), nNum) == absMin && gen1001(nNum) < retNum)))) {
absMin = diffULL(gen1001(nNum), nNum);
retNum = gen1001(nNum);
}
if (!absMin || (gen999(nNum) != nNum && (diffULL(gen999(nNum), nNum) < absMin || (diffULL(gen999(nNum), nNum) == absMin && gen999(nNum) < retNum)))) {
retNum = gen999(nNum);
}
return std::to_string(retNum);
}
}
};
int main() {
std::cout << Solution::nearestPalindromic("12389");
}

2
cpp/2203/CMakeLists.txt
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@ -3,4 +3,4 @@ PROJECT(2203)
SET(CMAKE_CXX_STANDARD 23)
ADD_EXECUTABLE(2203 220301.cpp)
ADD_EXECUTABLE(2203 220302-CN.cpp)