134 lines
3.3 KiB
C++
134 lines
3.3 KiB
C++
#pragma once
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#include <chrono>
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#include <iomanip>
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#include <iostream>
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#include <limits>
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#include <random>
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#include <string>
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class XorShift128Plus {
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private:
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uint64_t s[2];
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// 增强的字符串哈希
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static std::pair<uint64_t, uint64_t>
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hash_string_pair_std(const std::string &str) {
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std::hash<std::string> hasher;
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// 第一个哈希：原始字符串
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uint64_t hash1 = static_cast<uint64_t>(hasher(str));
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// 第二个哈希：反转字符串
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std::string reversed = str;
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std::reverse(reversed.begin(), reversed.end());
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uint64_t hash2 = static_cast<uint64_t>(hasher(reversed));
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// 如果字符串太短，添加额外混合
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if (str.length() < 4) {
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hash1 ^= 0x123456789ABCDEF0ULL;
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hash2 ^= 0x0FEDCBA987654321ULL;
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}
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return {hash1, hash2};
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}
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public:
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// 构造函数1：使用字符串作为种子
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XorShift128Plus(const std::string &seed_str) {
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auto seeds = hash_string_pair_std(seed_str);
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s[0] = seeds.first;
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s[1] = seeds.second;
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if (s[0] == 0 && s[1] == 0) {
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s[0] = 0x123456789ABCDEF0ULL;
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s[1] = 0x0FEDCBA987654321ULL;
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}
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// 预热，确保随机性
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for (int i = 0; i < 10; ++i) {
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next();
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}
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}
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// 构造函数2：使用两个64位整数作为种子
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XorShift128Plus(uint64_t seed1 = 0, uint64_t seed2 = 0) {
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if (seed1 == 0 && seed2 == 0) {
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std::random_device rd;
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// 正确组合rd()的结果到64位
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s[0] = (static_cast<uint64_t>(rd()) << 32) | rd();
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s[1] = (static_cast<uint64_t>(rd()) << 32) | rd();
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} else {
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s[0] = seed1;
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s[1] = seed2;
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}
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if (s[0] == 0 && s[1] == 0) {
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s[0] = 0x123456789ABCDEF0ULL;
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s[1] = 0x0FEDCBA987654321ULL;
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}
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// 预热
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for (int i = 0; i < 10; ++i) {
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next();
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}
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}
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// 正确的XorShift128Plus算法
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uint64_t next() {
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uint64_t x = s[0];
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uint64_t y = s[1];
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s[0] = y;
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x ^= x << 23;
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x ^= x >> 17;
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x ^= y ^ (y >> 26);
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s[1] = x;
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return s[1] + y;
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}
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// 获取[min, max]范围内的随机整数（无偏）
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int get_int(int min, int max) {
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if (min >= max)
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return min;
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uint32_t range = static_cast<uint32_t>(max - min + 1);
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// 拒绝采样法避免取模偏差
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uint32_t limit = std::numeric_limits<uint32_t>::max() -
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(std::numeric_limits<uint32_t>::max() % range);
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uint32_t raw;
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do {
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// 取next()的高32位（质量更好）
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raw = static_cast<uint32_t>(next() >> 32);
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} while (raw >= limit);
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return min + static_cast<int>(raw % range);
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}
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// 快速版本：当range是2的幂时使用
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int get_int_fast(int min, int max) {
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uint32_t range = max - min + 1;
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// 检查range是否是2的幂
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if (range > 0 && (range & (range - 1)) == 0) {
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uint64_t raw = next();
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return min + static_cast<int>(raw & (range - 1));
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}
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// 否则使用通用版本
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return get_int(min, max);
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}
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// 获取[0, 1)范围内的随机浮点数
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double get_double() {
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// 使用52位精度（IEEE 754双精度的尾数位）
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uint64_t bits = (next() >> 12) | 0x3FF0000000000000ULL;
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return *reinterpret_cast<double *>(&bits) - 1.0;
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}
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// 获取当前状态（用于调试）
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void get_state(uint64_t &s0, uint64_t &s1) const {
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s0 = s[0];
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s1 = s[1];
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}
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}; |