62 lines
2.9 KiB
C
62 lines
2.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/runtime/carsort.h"
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#include "libc/str/str.h"
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static textstartup size_t HeapSortMax(size_t n, int32_t A[n][2], long i, long j,
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long k) {
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if (j < n && A[j][0] > A[i][0]) i = j;
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if (k < n && A[k][0] > A[i][0]) i = k;
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return i;
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}
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static textstartup void HeapSortDown(size_t n, int32_t A[n][2], long i) {
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size_t j;
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int32_t t[2];
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for (;;) {
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j = HeapSortMax(n, A, i, 2 * i + 1, 2 * i + 2);
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if (j == i) break;
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memcpy(t, A[i], sizeof(t));
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memcpy(A[i], A[j], sizeof(t));
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memcpy(A[j], t, sizeof(t));
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i = j;
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}
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}
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/**
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* Sorts int32 key-value arrays of nontrivial size.
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*
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* @see test/libc/alg/carsort_test.c
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* @see carsort100() if smaller
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*/
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textstartup void carsort1000(size_t n, int32_t A[n][2]) {
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size_t i;
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int32_t t[2];
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for (i = ((n - 2) / 2) + 1; i > 0; i--) {
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HeapSortDown(n, A, i - 1);
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}
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for (i = 0; i < n; i++) {
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memcpy(t, A[n - i - 1], sizeof(t));
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memcpy(A[n - i - 1], A[0], sizeof(t));
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memcpy(A[0], t, sizeof(t));
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HeapSortDown(n - i - 1, A, 0);
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}
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}
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