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Co-authored-by: sigonasr2 <sigonasr2@gmail.com>
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sigonasr2, Sig, Sigo 2 years ago
parent f0d9bbfaeb
commit 0238e107c6
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  1. BIN
      archives/27/current
  2. 66
      archives/27/src/main.c
  3. 173
      archives/27/src/utils.c
  4. 16
      archives/27/src/utils.h
  5. BIN
      current
  6. 34
      src/main.c

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#include <stdio.h>
#include "utils.h"
/*
Euler discovered the remarkable quadratic formula:
It turns out that the formula will produce 40 primes for the consecutive integer values . However, when is divisible by 41, and certainly when is clearly divisible by 41.
The incredible formula was discovered, which produces 80 primes for the consecutive values . The product of the coefficients, −79 and 1601, is −126479.
Considering quadratics of the form:
, where and
where is the modulus/absolute value of
e.g. and
Find the product of the coefficients, and , for the quadratic expression that produces the maximum number of primes for consecutive values of , starting with .
https://projecteuler.net/problem=27
*/
int main(int argc,char**argv) {
FILE*f = fopen("archives/primegenerator/primes","r");
int startMarker=0;
while (fgetc(f)!='{') {
startMarker++;
}
int primes[2500];
char c;
int counter=0;
while (counter<2500) {
int digit=0;
while ((c=fgetc(f))!=',') {
digit*=10;
digit+=c-'0';
}
primes[counter++]=digit;
}
int n=0;
int maxLength=0;
int maxA=0;
int maxB=0;
for (int a=-999;a<1000;a++) {
for (int b=-999;b<=1000;b++) {
for (int p=0;p<2500;p++) {
if (n*n+a*n+b==primes[p]) {
n++;
p=0;
}
}
if (n>maxLength) {
maxLength=n;
maxA=a;
maxB=b;
printf("New max of %d found with n^2+%dn+%d\n",maxLength,maxA,maxB);
}
n=0;
}
}
printf("\n\nProduct of maxes (%d*%d)=%ld\n",maxA,maxB,(long)maxA*maxB);
return 0;
}

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#include "utils.h"
#include <stdio.h>
#include <stdlib.h>
struct String mult(struct String numb1, struct String numb2) {
struct String n1 = numb1;
struct String n2 = numb2;
byte carryover = 0;
if (numb2.length>numb1.length) {
n1=numb2;
n2=numb1;
}
int addends[n2.length][n1.length+1];
for (int i=0;i<n2.length;i++) {
for (int j=0;j<n1.length+1;j++) {
addends[i][j]=0;
}
}
for (int i=n2.length-1;i>=0;i--) {
carryover=0;
for (int j=n1.length-1;j>=0;j--) {
int mult = (n1.str[j]-'0')*(n2.str[i]-'0')+((carryover!=0)?carryover:0);
//printf(" %d/%d\n",mult,carryover);
carryover=0;
if (mult>=10) {
carryover=mult/10;
mult=mult%10;
}
addends[(n2.length-1)-i][j+1]=mult;
}
if (carryover>0) {
addends[(n2.length-1)-i][0]=carryover;
}
}
//printIntDoubleArr(n2.length,n1.length+1,addends);
struct String sum = {1,"0"};
for (int i=0;i<n2.length;i++) {
char val[n1.length+1+i];
for (int j=0;j<n1.length+1+i;j++) {
val[j]='0';
}
for (int j=0;j<n1.length+1;j++) {
val[j]=addends[i][j]+'0';
}
sum=add((struct String){n1.length+1+i,val},sum);
//printf("%s\n",sum.str);
}
if (sum.str[0]=='0') {
char*newStr=malloc(sum.length-1);
for (int i=1;i<sum.length;i++) {
newStr[i-1]=sum.str[i];
}
free(sum.str);
sum=(struct String){sum.length-1,newStr};
}
//printf("%s",sum.str);
return sum;
}
struct String add(struct String numb1, struct String numb2){
//printf("%s %s\n",numb1.str,numb2.str);
byte carryover=0;
int digitCount=0;
char*str = malloc(1);
//str[0]='\0';
if (numb1.length>=numb2.length) {
for (int offset=0;offset<numb1.length;offset++) {
str = realloc(str,++digitCount);
//printf("Digit count is now %d\n",digitCount);
if (numb2.length>offset) {
//printf("%c %c\n",numb1.str[numb1.length-offset-1],numb2.str[numb2.length-offset-1]);
int sum=((numb1.str[numb1.length-offset-1]-'0')+(numb2.str[numb2.length-offset-1]-'0'))+((carryover>0)?carryover--:0);
if (sum>=10) {
carryover=1;
sum-=10;
}
str[offset]=sum+'0';
} else {
str[offset]=numb1.str[numb1.length-offset-1]+((carryover>0)?carryover--:0);
}
//str[offset+1]='\0';
}
} else {
for (int offset=0;offset<numb2.length;offset++) {
str = realloc(str,++digitCount);
//printf("Digit count is now %d\n",digitCount);
if (numb1.length>offset) {
//printf("%c %c\n",numb1.str[numb1.length-offset-1],numb2.str[numb2.length-offset-1]);
int sum=((numb1.str[numb1.length-offset-1]-'0')+(numb2.str[numb2.length-offset-1]-'0'))+((carryover>0)?carryover--:0);
if (sum>=10) {
carryover=1;
sum-=10;
}
str[offset]=sum+'0';
} else {
str[offset]=numb2.str[numb2.length-offset-1]+((carryover>0)?carryover--:0);
}
//str[offset+1]='\0';
}
}
if (carryover>0) {
str = realloc(str,++digitCount);
str[digitCount-1]='1';
//str[digitCount]='\0';
}
for (int i=0;i<digitCount/2;i++) {
char c = str[i];
char c2 = str[digitCount-i-1];
str[digitCount-i-1]=c;
str[i]=c2;
}
str = realloc(str,digitCount+1);
str[digitCount]='\0';
struct String newStr = {digitCount,str};
return newStr;
}
void printLongDoubleArr(int a,int b,long doubleArr[a][b]) {
for (int i=0;i<a;i++) {
for (int j=0;j<b;j++) {
printf("%ld\t",doubleArr[i][j]);
}
printf("\n");
}
}
void printIntDoubleArr(int a,int b,int doubleArr[a][b]) {
for (int i=0;i<a;i++) {
for (int j=0;j<b;j++) {
printf("%d\t",doubleArr[i][j]);
}
printf("\n");
}
}
struct String createBigNumber(char*numb) {
int marker=0;
while (numb[marker++]!='\0');
return (struct String){marker-1,numb};
}
int*getFactors(int numb) {
int*factorList=malloc(sizeof(int)*1);
int factorListSize=2;
factorList[0]=1;
factorList[1]=numb;
int max=numb;
for (int i=2;i<max;i++) {
if (numb%i==0) {
factorList=realloc(factorList,sizeof(int)*++factorListSize);
factorList[factorListSize-1]=i;
if (numb/i!=i) {
factorList=realloc(factorList,sizeof(int)*++factorListSize);
factorList[factorListSize-1]=numb/i;
max=numb/i;
}
}
}
factorList=realloc(factorList,sizeof(int)*++factorListSize);
factorList[factorListSize-1]=0;
return factorList;
}
boolean isFactor(int*factorList,int numb) {
int counter=0;
while (factorList[counter]!=0) {
if (numb==factorList[counter]) {
return true;
}
counter++;
}
return false;
}

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#define true 1
#define false 0
#define boolean char
#define byte char
struct String{
int length;
char*str;
};
struct String add(struct String numb1, struct String numb2);
struct String mult(struct String numb1, struct String numb2);
void printLongDoubleArr(int a,int b,long doubleArr[a][b]);
void printIntDoubleArr(int a,int b,int doubleArr[a][b]);
struct String createBigNumber(char*numb);
#define BigNumber(X) createBigNumber(#X)
boolean isFactor(int*factorList,int numb);
int*getFactors(int numb);

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@ -26,15 +26,41 @@ int main(int argc,char**argv) {
while (fgetc(f)!='{') {
startMarker++;
}
fseek(f,startMarker,SEEK_SET);
int primes[2500];
char c;
int counter=0;
while (counter<2500) {
int digit=0;
while ((c=fgetc(f))!=',') {
digit*=10;
digit+=c-'0';
}
primes[counter++]=digit;
}
int n=0;
while (true) {
for (int a=1;a<1000;a++) {
for (int b=1;b<=1000;b++) {
int maxLength=0;
int maxA=0;
int maxB=0;
for (int a=-999;a<1000;a++) {
for (int b=-999;b<=1000;b++) {
for (int p=0;p<2500;p++) {
if (n*n+a*n+b==primes[p]) {
n++;
p=0;
}
}
if (n>maxLength) {
maxLength=n;
maxA=a;
maxB=b;
printf("New max of %d found with n^2+%dn+%d\n",maxLength,maxA,maxB);
}
n=0;
}
}
printf("\n\nProduct of maxes (%d*%d)=%ld\n",maxA,maxB,(long)maxA*maxB);
return 0;
}
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