Initial commit

odin/day01/day01.odin

@@ -0,0 +1,145 @@
+package day01
+
+import "core:fmt"
+import "core:os"
+import "core:math"
+import "core:strconv"
+
+scan_to_next :: proc(data: []byte, delim: byte, start_from: int) -> int {
+    for idx := start_from; idx < len(data); idx += 1 {
+        if data[idx] == '\n' {
+            return idx
+        }
+    }
+    return -1;
+}
+
+main_first_attempt :: proc () {
+    // Read in input file.
+    fh, errno := os.open("day01/calories-basic.input")
+    if errno != os.ERROR_NONE {
+        panic("Don't know what to do!")
+    }
+    defer os.close(fh)
+
+    line_start := 0 
+    line_end := -1
+    repr := 0
+    sum := 0
+    max := -1
+    content: []byte
+    ok: bool
+    content, ok = os.read_entire_file_from_handle(fh)
+    if !ok { return; }
+
+    for line_start < len(content) {
+
+        if content[line_start] == '\n' {
+            fmt.println(line_start, " starts a blank line: skipping to ", line_start + 1)
+            // Case: line is blank
+            // End summation; we are in a new group
+            max = math.max(max, sum)
+
+            // OK YOU NEED TO BE VERY CAREFUL WITH THIS! FIRST ODIN FOOTGUN!
+            // This line used to be `sum := 0` instead of `sum = 0` and I
+            // think that re-defined `sum` in this local scope because the
+            // total sum at the end was way too high; it never got reset to 0
+            // here. If you think about it, it makes sense... but I would think
+            // the compiler might warn me that I was shadowing something from
+            // ouside the scope...
+            sum = 0
+
+            // Go to next line
+            line_start += 1
+            continue
+        } 
+
+        line_end = scan_to_next(content, '\n', line_start + 1)
+        fmt.println("Next line: ", line_start, " thru ", line_end)
+
+        // Case: no newlines left
+        if line_end == -1 {
+            // Get last line
+            slc := string(content[line_start:len(content)])
+            repr, ok = strconv.parse_int(slc)
+            if !ok {
+                // Line doesn't have a number on it?
+                // TODO Just ignore for now
+            } else {
+                fmt.println("Result: ", repr, " Current Sum: ", sum + repr)
+                sum += repr
+                max = math.max(max, sum)
+                sum = 0
+            }
+            break
+        } 
+
+        // Case: Normal line with a number on it
+        slc := string(content[line_start:line_end])
+        fmt.println("Reading line: ", slc)
+        repr, ok = strconv.parse_int(slc)
+        if !ok {
+            // Line doesn't have a number on it?
+            // TODO Just ignore for now
+        } else {
+            fmt.println("Result: ", repr, " Current Sum: ", sum + repr)
+            sum += repr
+        }
+        line_start = line_end + 1
+    }
+    fmt.println("Largest group is ", max);
+}
+
+split_lines :: proc(data: []byte, delimiter: byte) -> [dynamic][]byte {
+    result: [dynamic][]byte
+    prev := 0 
+    idx: int
+    for idx = 0; idx < len(data); idx += 1 {
+        if data[idx] == delimiter {
+            append(&result, data[prev:idx])
+            prev = idx + 1
+        }
+    }
+    if prev < idx {
+        append(&result, data[prev:idx])
+    }
+    return result 
+}
+
+main :: proc() {
+    if len(os.args) < 2 {
+        fmt.printf("Usage: %s FILENAME\n", os.args[0])
+        os.exit(-1)
+    }
+    fh, errno := os.open(os.args[1])
+    if errno != os.ERROR_NONE {
+        fmt.printf("Cannot open %s: %s\n", os.args[1], os.get_last_error_string())
+        os.exit(int(errno))
+    }
+    defer os.close(fh)
+    content, ok := os.read_entire_file_from_handle(fh)
+    if !ok { 
+        fmt.printf("Cannot read %s: %s\n", os.args[1], os.get_last_error_string())
+        os.exit(-1)
+    }
+    lines := split_lines(content, '\n')
+    total := 0
+    max := 0
+    for line, idx in lines {
+        if len(line) == 0 {
+            max = math.max(max, total)
+            total = 0
+        } else {
+            x: int
+            s := string(line)
+            x, ok = strconv.parse_int(s)
+            if ok {
+                total += x
+            } else {
+                fmt.eprintf("Line %d: not a valid integer\n", idx)
+            }
+        }
+    }
+    max = math.max(total, max)
+    fmt.printf("Largest grouping: %d\n", max)
+}