src/data-structures/HashMap.h

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• Last update: 2025-07-17 00:10:13+09:00
• Link: http://codeforces.com/blog/entry/60737

Code

/**
 * Author: Simon Lindholm, chilli
 * Date: 2018-07-23
 * License: CC0
 * Source: http://codeforces.com/blog/entry/60737
 * Description: Hash map with mostly the same API as unordered\_map, but \tilde
 * 3x faster. Uses 1.5x memory.
 * Initial capacity must be a power of 2 (if provided).
 */
#pragma once

#include <bits/extc++.h> /** keep-include */
// To use most bits rather than just the lowest ones:
struct chash { // large odd number for C
	const uint64_t C = ll(4e18 * acos(0)) | 71;
	ll operator()(ll x) const { return __builtin_bswap64(x*C); }
};
__gnu_pbds::gp_hash_table<ll,int,chash> h({},{},{},{},{1<<16});

/** For CodeForces, or other places where hacking might be a problem:

const int RANDOM = chrono::high_resolution_clock::now().time_since_epoch().count();
struct chash { // To use most bits rather than just the lowest ones:
	const uint64_t C = ll(4e18 * acos(0)) | 71; // large odd number
	ll operator()(ll x) const { return __builtin_bswap64((x^RANDOM)*C); }
};
__gnu_pbds::gp_hash_table<ll, int, chash> h({},{},{},{}, {1 << 16});
*/

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.14.0/x64/lib/python3.14/site-packages/onlinejudge_verify/documentation/build.py", line 71, in _render_source_code_stat
    bundled_code = language.bundle(stat.path, basedir=basedir, options={'include_paths': [basedir]}).decode()
                   ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.14.0/x64/lib/python3.14/site-packages/onlinejudge_verify/languages/cplusplus.py", line 187, in bundle
    bundler.update(path)
    ~~~~~~~~~~~~~~^^^^^^
  File "/opt/hostedtoolcache/Python/3.14.0/x64/lib/python3.14/site-packages/onlinejudge_verify/languages/cplusplus_bundle.py", line 312, in update
    raise BundleErrorAt(path, i + 1, "#pragma once found in a non-first line")
onlinejudge_verify.languages.cplusplus_bundle.BundleErrorAt: src/data-structures/HashMap.h: line 10: #pragma once found in a non-first line

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