90 lines
1.3 KiB
C
90 lines
1.3 KiB
C
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/*
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* http://projecteuler.net
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*
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* Projecteuler - Problem 17
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* ------------------------
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* 2011-02-03 Henrik Hautakoski
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*/
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#include <stdio.h>
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#define N_AND 3
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#define N_HUNDRED 7
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#define N_THOUSAND 8
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int len_ones(int n) {
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switch(n) {
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case 1: case 2: case 6:
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return 3;
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case 4: case 5: case 9:
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return 4;
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case 3: case 7: case 8:
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return 5;
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}
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return 0;
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}
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int len_tentwenty(int n) {
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switch(n) {
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case 1: case 2:
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return 6;
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case 5: case 6:
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return 7;
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case 3: case 4: case 8: case 9:
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return 8;
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case 7:
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return 9;
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}
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return 0;
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}
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int len_tens(int n) {
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switch(n) {
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case 1:
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return 3;
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case 4: case 5: case 6:
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return 5;
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case 2: case 3: case 8: case 9:
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return 6;
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case 7:
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return 7;
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}
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return 0;
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}
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int len(int n) {
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int ret = 0;
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if (n > 99) {
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ret += len_ones(n / 100);
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n = n % 100;
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if (n)
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ret += N_AND;
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ret += N_HUNDRED;
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}
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if (n > 10 && n < 20) {
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ret += len_tentwenty(n % 10);
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} else {
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ret += len_ones(n % 10);
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ret += len_tens(n / 10);
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}
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return ret;
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}
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int main() {
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int i, n = len_ones(1) + N_THOUSAND;
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for(i=1; i < 1000; i++)
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n += len(i);
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printf("%i\n", n);
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return 0;
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}
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