011 ok

011/grid.txt

@@ -0,0 +1,20 @@
+08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
+49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
+81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
+52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
+22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
+24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
+32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
+67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
+24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
+21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
+78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
+16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
+86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
+19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
+04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
+88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
+04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
+20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
+20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
+01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48

011/main.rs

@@ -0,0 +1,105 @@
+use std::fs::File;
+use std::io::{ self, BufRead, BufReader };
+
+type Grid = Vec<Vec<u8>>;
+const N: usize = 20;
+
+fn read_grid_lines() -> io::Lines<BufReader<File>> {
+    let file = File::open("grid.txt").unwrap();
+    return io::BufReader::new(file).lines();
+}
+
+fn get_grid() -> Grid {
+    let lines = read_grid_lines();
+    let mut grid: Grid = Vec::new();
+    for line in lines {
+        let s = line.unwrap();
+        let ns: Vec<_>  = s.split(" ")
+                    .map(|x| x.parse::<u8>().unwrap())
+                    .collect();
+        grid.push(ns);
+    }
+    return grid;
+}
+
+fn g(grid: &Grid, i: usize, j: usize) -> u32 {
+    return u32::from(grid.get(i).unwrap().get(j).unwrap().clone());
+}
+
+fn best_h(grid: &Grid) -> u32 {
+    let mut best_pr = 1;
+    for i in 0..N {
+        for j in 0..N-3 {
+            let a = g(&grid, i, j);
+            let b = g(&grid, i, j + 1);
+            let c = g(&grid, i, j + 2);
+            let d = g(&grid, i, j + 3);
+            let pr = a * b * c * d;
+            if pr > best_pr { best_pr = pr; }
+        }
+    }
+    return best_pr;
+}
+
+fn best_v(grid: &Grid) -> u32 {
+    let mut best_pr = 1;
+    for i in 0..N-3 {
+        for j in 0..N {
+            let a = g(&grid, i, j);
+            let b = g(&grid, i + 1, j);
+            let c = g(&grid, i + 2, j);
+            let d = g(&grid, i + 3, j);
+            let pr = a * b * c * d;
+            if pr > best_pr { best_pr = pr; }
+        }
+    }
+    return best_pr;
+}
+
+fn best_dr(grid: &Grid) -> u32 {
+    let mut best_pr = 1;
+    for i in 0..N-3 {
+        for j in 0..N-3 {
+            let a = g(&grid, i, j);
+            let b = g(&grid, i + 1, j + 1);
+            let c = g(&grid, i + 2, j + 2);
+            let d = g(&grid, i + 3, j + 3);
+            let pr = a * b * c * d;
+            if pr > best_pr { best_pr = pr; }
+        }
+    }
+    return best_pr;
+}
+
+fn best_dl(grid: &Grid) -> u32 {
+    let mut best_pr = 1;
+    for i in 3..N {
+        for j in 0..N-3 {
+            let a = g(&grid, i, j);
+            let b = g(&grid, i - 1, j + 1);
+            let c = g(&grid, i - 2, j + 2);
+            let d = g(&grid, i - 3, j + 3);
+            let pr = a * b * c * d;
+            if pr > best_pr { best_pr = pr; }
+        }
+    }
+    return best_pr;
+}
+
+fn best(grid: &Grid) -> u32 {
+    let a = best_h(&grid);
+    let b = best_v(&grid);
+    let c = best_dr(&grid);
+    let d = best_dl(&grid);
+
+    println!("{} {} {} {}", a, b, c, d);
+
+    return best_h(&grid).max(best_v(&grid)).max(best_dr(&grid)).max(best_dl(grid));
+}
+
+fn main() {
+    let grid = get_grid();
+    let n = best(&grid);
+
+    println!("{}", n);
+}