Problems in the blog https://blog.csdn.net/qq_42120843/article/details/115391196? SPM=1001.2014.3001.5502, write here may length is too big, big trouble point a, the selfless help the younger brother thank you first

CodePudding user response:

The factorial function, int n type wrong, change of type double, int type for maximum: 2147483647, when accuracy take 0.01, n * fact (n - 1)=12! 14, 0.001! 16, 0.0001! When 13! When is beyond the scope of the n

CodePudding user response:

Fyi:

 # include & lt; Iostream> 
#include  
#include  
using namespace std; 
The inline int the COMPARE (string str1, string str2) {//return equal 0, is greater than the return 1, less than the return 1 
If (str1. The size () & gt; Str2. The size ()) return 1;//the length of the long integer greater than the length of the integer 
Else if (str1. The size () & lt; Str2. The size ()) return 1; 
The else pare said return str1.com (str2);//if equal length, head to tail according to the comparison of 
} 
String PLUS (string number1, string number2) {
int i; 
Int length1=number1. The size (); 
Int length2=number2. The size (); 

The string result=""; 

Reverse (number1. The begin (), number1. The end ()); 
Reverse (number2. The begin (), number2. The end ()); 

for(i=0; I & lt; Length1 & amp; & I & lt; Length2. I++) {
Char c=(char) (number1 number2 [I] + [I] - 48). 
Result=result + c; 
} 

While (I & lt; Length1) {
Result=result + number1 [I]; 
++i; 
} 

While (I & lt; Length2) {
Result=result + number2 [I]; 
++i; 
} 

Int carry=0; 
for(i=0; I & lt; (int) result. The size (); + + I) {
Int [I] value=https://bbs.csdn.net/topics/result - 48 + carry; 
The result [I]=(char) (value % 10 + 48); 
Carry=value/10; 
} 

If (carry!=0) {
Result=result + (char) + 48 (carry); 
} 

For (I=result. The size () - 1; I & gt;=0; I -) {
If (result [I]!='0') break; 
} 

Result=result. The substr (0, I + 1); 

Reverse (result. The begin (), the result. The end ()); 
If (result. The length ()==0) result="0"; 
return result; 
} 
String MULTIPLY (string number1, string number2) {
int i, j; 
Int * iresult; 
Int length1=number1. The size (); 
Int length2=number2. The size (); 
The string result=""; 

Reverse (number1. The begin (), number1. The end ()); 
Reverse (number2. The begin (), number2. The end ()); 

Iresult=(int *) malloc (sizeof (int) * (length1 + length2 + 1)); 
Memset (iresult, 0, sizeof (int) * (length1 + length2 + 1)); 

for(i=0; I & lt; Length1; I++) {
For (j=0; J & lt; Length2. J++) {
Iresult [I + j] +=((number1 [I] - 48) * (number2 [j] - 48)); 
} 
} 

Int carry=0; 
for(i=0; I & lt; Length1 + length2; I++) {
The int value=https://bbs.csdn.net/topics/iresult [I] + carry; 
Iresult=[I] value % 10; 
Carry=value/10; 
} 

For (I=length1 + length2-1; I & gt;=0; I -) {
If (iresult [I]!=0) break; 
} 

for(; I & gt;=0; I -) {
Result=result + (char) (iresult [I] + 48); 
} 

Free (iresult); 

If (result=="") result=" 0 "; 
return result; 
} 
The string of the factorial (string n) {
String temp="1"; 
The string I; 
For (I="1"; COMPARE (I, n) & lt;=0; I=PLUS (I, "1")) {
Temp=MULTIPLY (temp, I); 
} 
return temp; 
} 
Int main (void) {
Cout & lt; return 0; 
} 
//93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000 
//

CodePudding user response:

Again for reference:

 # include & lt; Iostream> 
#include  
using namespace std; 
The inline int the compare (string str1, string str2) {//return equal 0, is greater than the return 1, less than the return 1 
If (str1. The size () & gt; Str2. The size ()) return 1;//the length of the long integer greater than the length of the integer 
Else if (str1. The size () & lt; Str2. The size ()) return 1; 
The else pare said return str1.com (str2);//if equal length, head to tail according to the comparison of 
} 
String SUB_INT (string str1, string str2); 
String ADD_INT (string str1, string str2) {//high precision addition 
Int sign=1;//sign for the sign bit 
String STR. 
If (str1 [0]=='-') {
If (str2 [0]=='-') {
Sign=1; 
STR=ADD_INT (str1. Erase (0, 1), str2. Erase (0, 1)); 
} else {
STR=SUB_INT (str2, str1. Erase (0, 1)); 
} 
} else {
If (str2 [0]=='-') {
STR=SUB_INT (str1, str2. Erase (0, 1)); 
} else {//alignment, the two integers up short integer adding 0 
String: : size_type L1, L2, 
int i; 
L1=str1. The size (); 
L2=str2. The size (); 
If (L1 & lt; L2) {
for (i=1; i<=L2 - L1. I++) str1="0" + str1; 
} else {
for (i=1; i<=L1, L2, I++) str2="0" + str2; 
} 
Int int1=0, int2=0;//record int2 carry 
For (I=str1. The size () - 1; I>=0; I -) {
Int1=(int (str1 [I]) - '0' + int (str2 [I]) - '0' + int2) % 10; 
Int2=(int (str1 [I]) - '0' + int (str2 [I]) - '0' + int2)/10; 
STR=char (int1 + '0') + STR. 
} 
If (int2! STR==0) char (int2 + '0') + STR; 
} 
} 
//operation post-processing the sign bit 
If ((sign==1) & amp; & (STR [0]! STR='0'))="-" + STR; 
Return the STR; 
} 
String SUB_INT (string str1, string str2) {//high precision subtraction 
Int sign=1;//sign for the sign bit 
String STR. 
Int I, j; 
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