attemps from before

2021/day3/day3.zig

@@ -0,0 +1,85 @@
+const input = @embedFile("input3");
+const std = @import("std");
+
+pub fn main() !void{
+
+
+    var counting = [1]usize{0} ** 12;
+
+    var iter = std.mem.tokenize(u8, input, "\n");
+    while(iter.next() ) |line| {
+
+        for(line)|c, i|{
+            counting[i] += (c -48); //HACK: subtract 48 to go from ascii to bit
+        }
+
+
+        //@popCount(u8,line); // >=3 means 1 is most common bit.
+    }
+
+
+    //
+    var gamma:  u12 = 0;
+    var epsilon:u12 = 0;
+    
+    for(counting)|count, i|{
+
+        if(count > 500){
+            counting[i] = 1;
+        }else{
+            counting[i] = 0;
+        }
+    }
+
+
+    for(counting)|c, i|{
+        if(c == 1) gamma |= @as(u12, 1) << @intCast(u4,i ) ;
+    }
+
+    gamma = @bitReverse(u12, gamma);
+    epsilon = ~gamma;
+
+    const result: u64 = gamma * @as(u64, epsilon);
+
+    std.debug.print("result: {}", .{result});
+}
+
+test "part 1"{
+
+
+    var counting = [1]usize{0} ** 12;
+
+    var iter = std.mem.tokenize(u8, input, "\n");
+    while(iter.next() ) |line| {
+
+        for(line)|c, i|{
+            counting[i] += (c -48); //HACK: subtract 48 to go from ascii to bit
+        }
+
+    }
+
+
+    //
+    var gamma:  u12 = 0;
+    var epsilon:u12 = 0;
+    
+    for(counting)|count, i|{
+
+        if(count > 500){
+            counting[i] = 1;
+        }else{
+            counting[i] = 0;
+        }
+    }
+
+
+    for(counting)|c, i|{
+        if(c == 1) gamma |= @as(u12, 1) << @intCast(u4,i ) ;
+    }
+
+    gamma = @bitReverse(u12, gamma);
+    epsilon = ~gamma;
+    const result: u64 = gamma * @as(u64, epsilon);
+
+    std.testing.expect(2648450 == result);
+}

2021/day3/input3.test

@@ -0,0 +1,12 @@
+00100
+11110
+10110
+10111
+10101
+01111
+00111
+11100
+10000
+11001
+00010
+01010