AVLw @ 2023-10-03 17:22:12
超了五秒多。。不知道为啥 是vector太慢了吗 那也不至于这么慢吧 加了注释求大佬解答
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include<vector>
using namespace std;
//高精度减法
vector<int> sub(vector<int>& a, vector<int>& b) {
vector<int> c;
for (int i = 0, t = 0; i < a.size(); i++) {
t = a[i] - t;
if (i < b.size())
t -=b[i];
c.push_back((t + 10) % 10);
if (t < 0)
t = 1;
else
t = 0;
}
while (c.size() > 1 && c.back() == 0)
c.pop_back();
return c;
}
//高精度乘法
vector<int> mul2(vector<int>& a, vector<int>& b) {
vector<int>c(100010);
for (int i = 0; i < a.size(); i++) {
for (int j = 0; j < b.size(); j++) {
c[i + j] += a[i] * b[j];
c[i + j + 1] += c[i + j] / 10;
c[i + j] %= 10;
}
}
while (c.size() > 1 && c.back() == 0)
c.pop_back();
return c;
}
//高精度快速幂
vector<int> highPow(int n) { //2^n
vector<int>ans = { 1 }; vector<int> t = { 2 };
while (n) {
if (n & 1) {
ans = mul2(ans, t); //ans*=t
}
t = mul2(t, t); //t*=t
n >>= 1;
}
return ans;
}
int main() {
int p; scanf("%d", &p);
vector<int>ans;
ans = highPow(p);
cout << ans.size() << endl;
vector<int> tmp={1};
vector<int>res;
res=sub(ans, tmp); //2^p-1
res.resize(500); //不够500位填充0
for (int i = 499; i >=0; i--) {
if (i != 499 && (i+1) % 50 == 0)
cout << "\n" << res[i];
else
cout << res[i];
}
return 0;
}
by jzhjzh123 @ 2023-10-06 13:45:20
求幂时,一次乘2^30
by AVLw @ 2023-10-12 01:00:38
@jzhjzh123 什么意思 没懂求详解
by jzhjzh123 @ 2023-10-14 13:45:06
e...我那个方法好像有点问题,不过我的快速幂做法AC了,给你看一眼```cpp
using namespace std;
struct Bigint { int num[MAXNUM]; int len;
Bigint(int n = 0){
len = 0;
memset(num, 0, sizeof(num));
while(n){
num[len] = n%10;
n /= 10;
len ++;
}
len = 500;
}
int &operator[](int index){
return num[index];
}
void zhanPing(){
for(int i = 0;i < len;i ++){
num[i+1] += num[i] / 10;
num[i] %= 10;
}
}
void print(){
for(int i = len - 1;i >= 0;i --) cout << num[i];
}
void new_print(){
for(int i = 0;i < 10;i ++){
for(int j = 0;j < 50;j ++){
cout << num[len-1-(i*50+j)];
}
printf("\n");
}
}
};
Bigint operator(Bigint a, Bigint b){ Bigint c; for(int i = 0;i < a.len;i ++){ for(int j = 0;j < b.len;j ++) c[i+j] += a[i] b[j]; } c.zhanPing(); return c; }
Bigint pow2(int b){ Bigint chengShus[MAXNUM]; int i = 0; int powNum = b; Bigint chengShuNow(2); while(powNum){ if(powNum % 2){ chengShus[i++] = chengShuNow; powNum --; } else{ chengShuNow = chengShuNow chengShuNow; powNum /= 2; } } Bigint ans(1); while (i--) { ans = ans chengShus[i]; }
return ans;
}
int main(){ int p; cin >> p; double log2 = log10(2); cout << (int)(p * log2 + 1) << endl; Bigint ans(1);
ans = pow2(p);
ans[0] --;
ans.new_print();
return 0;
}
by jzhjzh123 @ 2023-10-14 13:45:47
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
#define MAXNUM 1000
struct Bigint {
int num[MAXNUM];
int len;
Bigint(int n = 0){
len = 0;
memset(num, 0, sizeof(num));
while(n){
num[len] = n%10;
n /= 10;
len ++;
}
len = 500;
}
int &operator[](int index){
return num[index];
}
void zhanPing(){
for(int i = 0;i < len;i ++){
num[i+1] += num[i] / 10;
num[i] %= 10;
}
}
void print(){
for(int i = len - 1;i >= 0;i --) cout << num[i];
}
void new_print(){
for(int i = 0;i < 10;i ++){
for(int j = 0;j < 50;j ++){
cout << num[len-1-(i*50+j)];
}
printf("\n");
}
}
};
Bigint operator*(Bigint a, Bigint b){
Bigint c;
for(int i = 0;i < a.len;i ++){
for(int j = 0;j < b.len;j ++)
c[i+j] += a[i] * b[j];
}
c.zhanPing();
return c;
}
Bigint pow2(int b){
Bigint chengShus[MAXNUM];
int i = 0;
int powNum = b;
Bigint chengShuNow(2);
while(powNum){
if(powNum % 2){
chengShus[i++] = chengShuNow;
powNum --;
}
else{
chengShuNow = chengShuNow * chengShuNow;
powNum /= 2;
}
}
Bigint ans(1);
while (i--)
{
ans = ans * chengShus[i];
}
return ans;
}
int main(){
int p;
cin >> p;
double log2 = log10(2);
cout << (int)(p * log2 + 1) << endl;
Bigint ans(1);
ans = pow2(p);
ans[0] --;
ans.new_print();
return 0;
}
by jzhjzh123 @ 2023-10-14 13:47:12
快速幂思路来自:快速幂