《算法笔记》P170
乘除法没弄,书上说不常考~
代码:
#include <stdio.h>
#include <string.h>
//结构体中初始化
struct bign{
int d[1000];
int len;
bign(){
memset(d,0,sizeof(d));
len = 0;
}
};
//将str读入的数据赋值给数组
bign change(char str[]){
bign a;
a.len = strlen(str);
for(int i = 0;i <a.len;i++){
a.d[i] = str[a.len - i -1] - '0';
}
return a;
}
//比较大小
int compare(bign a,bign b){
if(a.len >b.len) return 1;
else if(a.len <b.len) return -1;
else{
for(int i = a.len-1;i>=0;i--){
if(a.d[i]>b.d[i]) return 1;
else if(a.d[i] <b.d[i]) return -1;
}
return 0;
}
}
//高精度加法
bign add(bign a,bign b){
bign c;
int carry = 0;
for(int i = 0;i <a.len || i<b.len;i++){
int temp = a.d[i] + b.d[i] + carry;
c.d[c.len++] = temp%10;
carry = temp / 10;
}
if(carry != 0){
c.d[c.len++] = carry;
}
return c;
}
//输出函数
void print(bign a){
for(int i = a.len - 1;i >= 0;i--){
printf("%d",a.d[i]);
}
}
//高精度减法
bign sub(bign a,bign b){
bign c;
for(int i = 0;i <a.len || i <b.len;i++){
if(a.d[i]<b.d[i]){
a.d[i+1]--;
a.d[i] += 10;
}
c.d[c.len++] = a.d[i] - b.d[i];
}
while(c.len - 1>= 1 && c.d[c.len - 1] == 0){
c.len--;
}
return c;
}
int main(){
char str1[1000],str2[1000];
scanf("%s%s",str1,str2);
bign a = change(str1);
bign b = change(str2);
print(add(a,b));
printf("\n");
//减法使用要先比较大小,看是否需要交换
if(compare(a,b) == 1){
print(sub(a,b));
}
else if(compare(a,b) == 0){
printf("0\n");
}
else{
bign temp = a;
a = b;
b = temp;
printf("-");
print(sub(a,b));
}
return 0;
}