C++大数乘法
写着玩，时间复杂度极高
//#include<bits/stdc++.h>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
char one[1]={'1'},fir_[1000000]={'\0'},fir[1000000]={'\0'},sec[1000000]={'\0'},sec_[1000000]={'\0'},count_[1000000]={'\0'},count[1000000]={'\0'},last[1000000]={'\0'};
char plus_show(char *fir,char *sec,char *last);
char plus(char *fir,char *sec,char *last);
int main(){
scanf("%s",fir);
scanf("%s",sec);
count[0]='1';
strcpy(fir_,fir);
//printf("fir_:%s\n",fir_);
while(1){
//printf("%d %s\n",strcoll(count,sec),last);
if(strcoll(count,sec)==0&&sec[0]=='1'&&strlen(sec)==1){
printf("%s\n",fir);
return 0;
}
else if(strcoll(count,sec)==0){
printf("%s\n",last);
return 0;
}
else{
plus(fir,fir_,last);//加法
/*for(int nm=0;nm<strlen(fir_);nm++){
fir_[nm]='\0';
}*/
strcpy(fir_,last);
/*for(int nm=0;nm<strlen(last);nm++){
last[nm]='\0';
}*/
plus(one,count,count_);//count++
//printf("count_:%s\n",count_);
/*for(int nm=0;nm<strlen(count);nm++){
count[nm]='\0';
}*/
strcpy(count,count_);
//printf("count:%s\n",count);
/*for(int nm=0;nm<strlen(count_);nm++){
count_[nm]='\0';
}*/
}
}
return 0;
}
char plus(char *fir,char *sec,char *last){
int i,j,k;
i=j=k=0;
int first=0,second=0,judge=0,judge_=0;
//printf("this is a program about plus.\n");
//printf("first number:\n");
//printf("second number:\n");
first=strlen(fir);
second=strlen(sec);
//printf("%d\n",first);
//printf("%d\n",second);
judge=judge_=0;
if(first>second){
for(i=second-1,j=first-1;i>=0;j--,i--){
judge=fir[j]-48+sec[i]-48;
if(judge>9&&judge_==0){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge>9&&judge_==1){
judge=judge+1;
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge<=9&&judge_==1){
judge=judge+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else{
last[j]=judge+48;
judge_=0;
}
}
else if(judge<=9&&judge_==0){
last[j]=judge+48;
judge_=0;
}
}
for(i=first-second-1;i>=0;i--){
if(judge_==0){
last[i]=fir[i];
judge_=0;
}
else if(judge_==1){
judge=fir[i]-48+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[i]=judge+48;
}
else{
judge_=0;
last[i]=judge+48;
}
}
}
if(judge_==1){
int li;
li=strlen(last)+1;
for(i=li;i>=1;i--){
last[i]=last[i-1];
}
last[0]='1';
}
//printf("%s\n",last);
}
else if(first<second){
for(i=first-1,j=second-1;i>=0;j--,i--){
judge=sec[j]-48+fir[i]-48;
if(judge>9&&judge_==0){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge>9&&judge_==1){
judge=judge+1;
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge<=9&&judge_==1){
judge=judge+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else{
last[j]=judge+48;
judge_=0;
}
}
else if(judge<=9&&judge_==0){
last[j]=judge+48;
judge_=0;
}
}
for(i=-first+second-1;i>=0;i--){
if(judge_==0){
last[i]=sec[i];
judge_=0;
}
else if(judge_==1){
judge=sec[i]-48+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[i]=judge+48;
}
else{
judge_=0;
last[i]=judge+48;
}
}
}
if(judge_==1){
int li;
li=strlen(last)+1;
for(i=li;i>=1;i--){
last[i]=last[i-1];
}
last[0]='1';
}
//printf("%s\n",last);
}
else{
for(i=second-1,j=first-1;i>=0;j--,i--){
judge=fir[j]-48+sec[i]-48;
if(judge>9&&judge_==0){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge>9&&judge_==1){
judge=judge+1;
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge<=9&&judge_==1){
judge=judge+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else{
last[j]=judge+48;
judge_=0;
}
}
else if(judge<=9&&judge_==0){
last[j]=judge+48;
judge_=0;
}
}
if(judge_==1){
int li;
li=strlen(last)+1;
for(i=li;i>=1;i--){
last[i]=last[i-1];
}
last[0]='1';
}
//printf("%s\n",last);
}
}
char plus_show(char *fir,char *sec,char *last){
int i,j,k;
i=j=k=0;
int first=0,second=0,judge=0,judge_=0;
//printf("this is a program about plus.\n");
//printf("first number:\n");
//printf("second number:\n");
first=strlen(fir);
second=strlen(sec);
//printf("%d\n",first);
//printf("%d\n",second);
judge=judge_=0;
if(first>second){
for(i=second-1,j=first-1;i>=0;j--,i--){
judge=fir[j]-48+sec[i]-48;
if(judge>9&&judge_==0){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge>9&&judge_==1){
judge=judge+1;
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge<=9&&judge_==1){
judge=judge+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else{
last[j]=judge+48;
judge_=0;
}
}
else if(judge<=9&&judge_==0){
last[j]=judge+48;
judge_=0;
}
}
for(i=first-second-1;i>=0;i--){
if(judge_==0){
last[i]=fir[i];
judge_=0;
}
else if(judge_==1){
judge=fir[i]-48+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[i]=judge+48;
}
else{
judge_=0;
last[i]=judge+48;
}
}
}
if(judge_==1){
int li;
li=strlen(last)+1;
for(i=li;i>=1;i--){
last[i]=last[i-1];
}
last[0]='1';
}
printf("%s\n",last);
}
else if(first<second){
for(i=first-1,j=second-1;i>=0;j--,i--){
judge=sec[j]-48+fir[i]-48;
if(judge>9&&judge_==0){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge>9&&judge_==1){
judge=judge+1;
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge<=9&&judge_==1){
judge=judge+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else{
last[j]=judge+48;
judge_=0;
}
}
else if(judge<=9&&judge_==0){
last[j]=judge+48;
judge_=0;
}
}
for(i=-first+second-1;i>=0;i--){
if(judge_==0){
last[i]=sec[i];
judge_=0;
}
else if(judge_==1){
judge=sec[i]-48+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[i]=judge+48;
}
else{
judge_=0;
last[i]=judge+48;
}
}
}
if(judge_==1){
int li;
li=strlen(last)+1;
for(i=li;i>=1;i--){
last[i]=last[i-1];
}
last[0]='1';
}
printf("%s\n",last);
}
else{
for(i=second-1,j=first-1;i>=0;j--,i--){
judge=fir[j]-48+sec[i]-48;
if(judge>9&&judge_==0){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge>9&&judge_==1){
judge=judge+1;
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else if(judge<=9&&judge_==1){
judge=judge+1;
if(judge>9){
judge_=1;
judge=judge%10;
last[j]=judge+48;
}
else{
last[j]=judge+48;
judge_=0;
}
}
else if(judge<=9&&judge_==0){
last[j]=judge+48;
judge_=0;
}
}
if(judge_==1){
int li;
li=strlen(last)+1;
for(i=li;i>=1;i--){
last[i]=last[i-1];
}
last[0]='1';
}
printf("%s\n",last);
}
}
