ZYM/BH-int2048-2023
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fix: 修复边界情况求解的bug

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This commit is contained in:
ZhuangYumin
2023-11-01 17:20:27 +08:00
parent 7b2db73aaa
commit 4bfcf1e5d6
2 changed files with 23 additions and 10 deletions
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29
src/int2048.cpp
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@ -27,6 +27,7 @@
#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <utility>
static_assert(sizeof(int) == 4, "sizeof(int) != 4");
@ -577,20 +578,21 @@ void int2048::UnsignedMultiplyByInt(int v) {
}
/**
* @brief Estimate the inverse of B, which is the result of [(base)^2n/B]
* @brief Estimate the inverse of B, which is the result of [10^2n/B]
*/
int2048 GetInv(const int2048 &B, int n) {
const static int kPow10[9] = {1, 10, 100, 1000, 10000,
100000, 1000000, 10000000, 100000000};
int total_blocks = (B.num_length + int2048::kNum - 1) / int2048::kNum;
if (n <= 16) {
long long b = B.val[total_blocks - 1] * (long long)int2048::kStoreBase +
B.val[total_blocks - 2];
long long b = 0;
for (int j = B.num_length - 1, i = 0; i < n; i++, j--)
b = b * 10 + (B.val[j / int2048::kNum] / kPow10[j % int2048::kNum]) % 10;
int2048 res;
res.ClaimMem((2 * n) + 1);
res.val[2 * n / int2048::kNum] = kPow10[2 * n % int2048::kNum];
__uint128_t c = 0;
int tmp_B = (((2 * n) + 1) - int2048::kNum - 1) / int2048::kNum;
int tmp_B = (((2 * n) + 1) + int2048::kNum - 1) / int2048::kNum;
for (int i = tmp_B - 1; i >= 0; i--) {
c = c * int2048::kStoreBase + res.val[i];
res.val[i] = c / b;
@ -611,12 +613,21 @@ int2048 GetInv(const int2048 &B, int n) {
int2048 sub_soluton_copy_2(sub_soluton);
sub_soluton_copy_1.UnsignedMultiplyByInt(2);
sub_soluton_copy_1.LeftMoveBy((n - k));
int2048 current_B; // current_B is the highest n numbers of B
/*now we get the current B*/
int2048 current_B;
current_B.ClaimMem(n);
int current_B_blocks = (n + int2048::kNum - 1) / int2048::kNum;
for (int i = current_B_blocks - 1; i >= 0; i--)
current_B.val[i] = B.val[i + total_blocks - current_B_blocks];
current_B.num_length = B.num_length - (total_blocks - current_B_blocks);
for (int i = B.num_length - 1, j = n - 1; j >= 0; j--, i--)
current_B.val[j / int2048::kNum] +=
(B.val[i / int2048::kNum] / kPow10[i % int2048::kNum] % 10) *
kPow10[j % int2048::kNum];
// current_B is the highest n numbers of B
current_B.num_length = n;
// std::cerr << "n=" << n << " while B=";
// int2048 new_B = B;
// new_B.print_debug();
// std::cerr << "current_B: ";
// current_B.print_debug();
UnsignedMultiply(sub_soluton_copy_2, &current_B);
UnsignedMultiply(sub_soluton_copy_2, &sub_soluton);
sub_soluton_copy_2.RightMoveBy(2 * k);

4
tester/cases/3.py
View File

@ -36,7 +36,9 @@ opt_python=[]
if True:
for i in range(0,10):
val=randint(-10**1000,10**1000)
val=randint(-10**100,10**100)
if i==0:
val=randint(-10**100,10**100)
opt_cpp.append("a_"+str(i)+"=int2048(\""+str(val)+"\");")
opt_python.append("a_"+str(i)+"="+str(val))
opt_cpp.append("a_"+str(i)+".print(); puts(\"\");")