58 lines
762 B
C
58 lines
762 B
C
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/*
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* http://projecteuler.net
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*
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* Projecteuler - Problem 4
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* ------------------------
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* 2009-12-28 Henrik Hautakoski
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*
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* A somewhat elegant solution (representing the numbers as a string is not so fancy)
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*/
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#include <stdio.h>
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int factor(int val) {
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int a;
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for(a=999; a > 99; a--) {
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if((val % a) == 0 && (val/a) < 999)
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return a;
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}
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return 0;
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}
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int ispalindrom(int num) {
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int i, n;
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char buffer[7];
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sprintf(buffer, "%i", num);
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for(n=0; buffer[n+1] != 0; n++);
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for(i=0; i < n-i; i++) {
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if (buffer[i] != buffer[n-i])
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return 0;
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}
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return 1;
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}
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int main() {
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int r, a;
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for(r=999999; r >= 100001; r--) {
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if (!ispalindrom(r) || !(a = factor(r)))
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continue;
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printf("%i\n", r);
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break;
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}
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return 0;
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}
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