97 lines
1.8 KiB
C
97 lines
1.8 KiB
C
/*
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Dial from 0–99, start at 50.
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You get lines like L68 or R5:
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L = move left (subtract)
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R = move right (add)
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Wrap around with modulo 100.
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After each move, check if the dial is on 0.
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The password = how many times you land on 0 during the whole sequence.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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int main(int argc, char* argv[]) {
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printf("Advent Of Code Day 1 part 2\n\n");
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// remove argc so gcc wont cry
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(void)argc;
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// base vars
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int start = 50;
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int pos = start;
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int counter = 0;
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// read the input file
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char* inpf = NULL;
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inpf = argv[1];
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if (inpf == NULL) inpf = "input.txt";
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FILE* ptr = fopen(inpf, "r");
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if(ptr == NULL) {
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printf("error: no such file %s\n", inpf);
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return 1;
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}
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printf("first position: %d\n", pos);
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// process instructions
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char line[9]; // 8 chars + eol
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while(fscanf(ptr, "%9s", line) == 1) {
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char drc = line[0];
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int num = atoi(&line[1]);
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printf("%c %d\n", drc, num);
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//if (drc == 'R') pos += num;
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//if (drc == 'L') pos -= num;
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if (drc == 'R') {
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for(int i = 0; i < num; i++) {
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if (pos + 1 < 100) {
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pos += 1;
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} else {
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pos += 1;
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pos -= 100;
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//printf("overflow -=100\n");
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}
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if (pos == 0) counter++;
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}
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}
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if (drc == 'L') {
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for (int i = 0; i < num; i++) {
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if (pos - 1 >= 0) {
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pos -= 1;
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} else {
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pos -= 1;
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pos += 100;
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}
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if (pos == 0) counter++;
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}
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}
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while (pos > 99) {
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//pos -= 100;
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for (int i = 0; i < 100; i++) {
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if (pos == 0) counter++;
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pos -= 1;
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}
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}
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while (pos < 0){
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//pos += 100;
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for (int i = 0; i < 100; i++) {
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if (pos == 0) counter++;
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pos += 1;
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}
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}
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//if (pos == 0) counter++;
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printf("current position: %d\n", pos);
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printf("counter is: %d\n", counter);
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}
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//printf("current position: %d\n", pos);
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printf("\npassword is: %d\n", counter);
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return 0;
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}
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