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-rw-r--r--.gitignore2
-rw-r--r--03/.gitignore1
-rw-r--r--03/main.cc89
-rw-r--r--03/makefile4
4 files changed, 95 insertions, 1 deletions
diff --git a/.gitignore b/.gitignore
index e427dd8..8225d36 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1 @@
-*/input.txt
+*/*.txt
diff --git a/03/.gitignore b/03/.gitignore
new file mode 100644
index 0000000..ba2906d
--- /dev/null
+++ b/03/.gitignore
@@ -0,0 +1 @@
+main
diff --git a/03/main.cc b/03/main.cc
new file mode 100644
index 0000000..b452c95
--- /dev/null
+++ b/03/main.cc
@@ -0,0 +1,89 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+const vector<char> SYMBOLS = {'#', '$', '%', '&', '*', '+', '-', '/', '=', '@'};
+const vector<char> NUMBERS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};
+
+int main() {
+ // phase 1 -- read lines into buffer
+ vector<string> lines;
+ for (string line; getline(cin, line);)
+ lines.push_back(line);
+ size_t rows = lines.size();
+ size_t cols = lines[0].size();
+
+ // phase 2 -- create valid number mask
+ vector<vector<bool>> valid_mask(rows, vector<bool>(cols, false));
+ for (int i = 0; i < rows; i++) {
+ for (int j = 0; j < cols; j++) {
+ // row and column offset for checking diagonals too
+ for (int roff = -1; roff <= 1; roff++) {
+ for (int coff = -1; coff <= 1; coff++) {
+ // skip any x,y coordinates that are outide the "grid"
+ int y = i + roff;
+ if (y < 0) continue;
+ if (y >= rows) continue;
+ int x = j + coff;
+ if (x < 0) continue;
+ if (x >= cols) continue;
+
+ for (char symbol : SYMBOLS)
+ if (lines[y][x] == symbol)
+ valid_mask[i][j] = true;
+ }
+ }
+ }
+ }
+
+ for (int i = 0; i < rows; i++) {
+ for (int j = 0; j < cols; j++)
+ printf("%c", lines[i][j]);
+ printf("\n");
+ }
+ for (int i = 0; i < rows; i++) {
+ for (int j = 0; j < cols; j++)
+ printf("%c", valid_mask[i][j] ? 'x' : ' ');
+ printf("\n");
+ }
+
+ // phase 3 -- read each number and add to output if any of its digits are
+ // true in valid_mask
+ int output = 0;
+ int digit = 0;
+ int valid_digit = false;
+ for (int i = 0; i < rows; i++) {
+ for (int j = 0; j < cols; j++) {
+ char cell = lines[i][j];
+ bool valid = valid_mask[i][j];
+ int last_digit = digit;
+ for (char num : NUMBERS) {
+ if (cell != num)
+ continue;
+
+ // printf("[%c]", cell);
+ digit *= 10;
+ digit += cell - '0';
+ if (valid)
+ valid_digit = true;
+ }
+ if (digit == last_digit && digit != 0) {
+ // printf(" (inline, %d, %s)\n", digit, valid_digit ? "valid" : "not valid");
+ if (valid_digit)
+ output += digit;
+ digit = 0;
+ valid_digit = false;
+ }
+ }
+ if (digit != 0) {
+ // printf(" (EOL, %d, %s)\n", digit, valid_digit ? "valid" : "not valid");
+ if (valid_digit)
+ output += digit;
+ digit = 0;
+ valid_digit = false;
+ }
+ }
+
+ printf(">> %d\n", output);
+
+ return 0;
+}
diff --git a/03/makefile b/03/makefile
new file mode 100644
index 0000000..a78e3da
--- /dev/null
+++ b/03/makefile
@@ -0,0 +1,4 @@
+main: main.cc
+clean:
+ $(RM) main
+