79 lines
1.6 KiB
C
79 lines
1.6 KiB
C
#include <ctype.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdbool.h>
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/*
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* Each line of the input file contains a string with a mix of letters and digits
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* Each line's "calibration value" is a single two digit number, made up of the first and last
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* digit found in the string
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* Print out the sum of all the calibration values.
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*/
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char buffer[2048];
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void read_line(char* linebuf, FILE* file)
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{
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char* str = fgets(linebuf, 2048, file);
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if (feof(file))
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{
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return;
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}
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if (str == NULL)
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{
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fprintf(stderr, "Fgets error");
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linebuf[0] = '\0';
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}
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}
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void extract_digits(char* str, char *first, char *last)
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{
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char *p,*q,*r;
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p = str;
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while (*p != '\0' && !isdigit(*p))
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p++; // find first digit
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*first = *last = *p;
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q = p;
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while (*q != '\0') // find digits until end of string
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{
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q++;
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if (isdigit(*q))
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{
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*last = *q;
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}
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}
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}
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long convert_chars(char first, char last)
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{
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char num[3] = { first, last, '\0' };
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return strtoul(num, NULL, 10);
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}
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int main(int argc, char *argv[])
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{
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FILE* input = fopen("input", "r");
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if (input == NULL)
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{
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fprintf(stderr, "error opening file");
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return EXIT_FAILURE;
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}
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long sum = 0;
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char first, last;
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while(true)
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{
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read_line(buffer, input);
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if (feof(input))
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break;
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extract_digits(buffer, &first, &last);
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long value = convert_chars(first, last);
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printf("%ld\t%s", value, buffer);
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sum += value;
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}
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printf("%ld", sum);
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return EXIT_SUCCESS;
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}
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