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Max_Product_Palindrome.c
100 lines (84 loc) · 1.66 KB
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Max_Product_Palindrome.c
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#include "stdio.h"
#include "string.h"
#include "stdlib.h"
#define DIGITS 3
// return a^b
int pow1(int a, int b)
{
int i = 0;
float num = 1;
for(i=0; i<b; i++)
{
num = num*a;
}
return num;
}
void setChar(int num, char *str, int i)
{
//printf("IsPalindrome str = %d\n",str);
str[i] = num + '0';
//printf("IsPalindrome char = %c\n",str[i]);
}
void Itoa(int num, char *str)
{
int p = 0, q = 0, r = 0;
int i = 0;
//printf("IsPalindrome str = %d\n",str);
while(num)
{
p = (num/10)*10;
q = num - p;
setChar(q, str, i); // put q converted to character in str[i]
num = num/10;
i++;
}
str[i] = '\0';
}
int IsPalindrome(int num)
{
char *str = (char *) malloc(2*DIGITS);
//printf("IsPalindrome num = %d\n",num);
Itoa(num, str);
int len = strlen(str);
//printf("IsPalindrome str = %s\n",str);
int start = 0;
int end = len-1;
while(start < end)
{
if(str[start] != str[end])
{
return 0;
}
start++;
end--;
}
return 1;
}
int MaxProduct()
{
int min = pow1(10,DIGITS-1);
int max = 0;
int i = 0;
int num1 = 0, num2 = 0;
int maxProduct = 0;
for(i=0; i<DIGITS; i++)
{
max = max*10 + 9;
}
for(num1=max; num1 >= min; num1--)
{
for(num2=num1-1; num2 >= min; num2--)
{
if(IsPalindrome(num1*num2))
{
maxProduct = maxProduct < num1*num2 ? num1*num2 : maxProduct;
}
}
}
return maxProduct;
}
int main()
{
printf("maxProduct = %d\n",MaxProduct());
return 0;
}