solved 10a and b

10/input

@@ -0,0 +1,53 @@
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10/inputDemo

@@ -0,0 +1,8 @@
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+10456732

10/main.c

@@ -0,0 +1,127 @@
+#include<stdlib.h>
+#include<stdio.h>
+#include<string.h>
+#include<stdbool.h>
+
+struct list {
+	int xy[2];
+	struct list *next;
+};
+
+int score_trail(int x, int y, int width, int height, char **map, struct list *peaks)
+{
+	int dir[4][2] = {{0, -1}, {1, 0}, {0, 1}, {-1, 0}};
+	int score = 0;
+	int first = map[x][y];
+
+	// init list
+	if (peaks == NULL) {
+		peaks = malloc(sizeof(struct list));
+		peaks->xy[0] = -1;
+		peaks->xy[1] = -1;
+		peaks->next = NULL;
+	}
+
+	// if find 9, check if its already in list, else append it
+	// could have been its own func
+	if (map[x][y] == '9') {
+		printf("found %dx%d\n", x, y);
+		if (peaks->xy[0] == -1 ) {
+			printf("was first, init first trail\n");
+			peaks->xy[0] = x;
+			peaks->xy[1] = y;
+			return 1;
+		}
+		// while (!(peaks->xy[0] == x && peaks->xy[1] == y) && peaks->next) {
+		while (peaks->next) {
+			printf("checking next peaklist...\n");
+			peaks = peaks->next;
+		}
+		/*
+		if (peaks->xy[0] == x && peaks->xy[1] == y) {
+			printf("found same, exit\n");
+			return 0;
+		}
+		*/
+		// printf("allocate new peak, jump to it, and set it\n");
+		peaks->next = malloc(sizeof(struct list));
+		peaks = peaks->next;
+		peaks->xy[0] = x;
+		peaks->xy[1] = y;
+		peaks->next = NULL;
+		return 1;
+	}
+
+	// look in every direction for grid[j][i] + 1, recurse it
+	for (int i = 0; i < 4; i++) {
+		if (x + dir[i][0] >= 0 &&
+		    x + dir[i][0] < width &&
+		    y + dir[i][1] >= 0 &&
+		    y + dir[i][1] < height) {
+			if (map[x + dir[i][0]][y + dir[i][1]] == map[x][y] + 1)
+				score_trail(x + dir[i][0], y + dir[i][1],
+				            width, height, map, peaks);
+		}
+	}
+
+	// please count and cleanup the list
+	if (first == '0') {
+		struct list *tmp;
+		while (peaks) {
+			score++;
+			tmp = peaks;
+			peaks = peaks->next;
+			free(tmp);
+		}
+		return score;
+	}
+	return 0;
+}
+
+int main ()
+{
+
+	// figure out data dimensions
+	FILE *input = fopen("./input", "r");
+	int width =  0;
+	int height = 1;
+	while (fgetc(input) != '\n') width++;
+	for (char c = fgetc(input); c != EOF; c = fgetc(input)) {
+		if (c == '\n')
+			height++;
+	}
+	rewind(input);
+	printf("Dimensions: %d x %d\n", width, height);
+
+	// make 2d array
+	char **map = malloc(width * sizeof(char*));
+	map[0] = malloc(width * height);
+	for (int i = 1; i < width; i++) {
+		map[i] = map[0] + i * height;
+	}
+
+	// put the data in the array
+	for (int i = 0; i < height; i++) {
+		for (int j = 0; j < width; j++) {
+			map[j][i] = fgetc(input);
+		}
+		fgetc(input);
+	}
+	fclose(input);
+
+	// sum it
+	int scoreSum = 0;
+	// find trailheads, check their score, sumit (hehehe)
+	for (int i = 0; i < height; i++) {
+		for (int j = 0; j < width; j++) {
+			if (map[j][i] == '0') {
+				printf("\tExamining %dx%d:\n", j, i);
+				int score = score_trail(j, i, width, height, map, NULL);
+				scoreSum += score;
+				if (score)
+					printf("score sum trail head %dx%d: %d\n", j, i, score);
+			}
+		}
+	}
+	printf("total score: %d\n", scoreSum);
+}