54. 螺旋矩阵

src/main.rs

@@ -1,106 +1,62 @@
-enum Operation {
-    Add,
-    Subtract,
-    Multiply,
-    Divide,
-}
-enum Card {
-    Int(i32),
-    Op(Operation),
-}
 struct Solution;
 impl Solution {
-    fn solve(cards: &Vec<Card>) -> bool {
-        let mut stack = Vec::new();
-        for t in cards.iter() {
-            if let Card::Op(op) = t {
-                if stack.len() < 2 {
-                    return false;
-                }
-                let b = stack.pop().unwrap() as f64;
-                let a = stack.pop().unwrap() as f64;
-                let result = match op {
-                    Operation::Add => a + b,
-                    Operation::Subtract => a - b,
-                    Operation::Multiply => a * b,
-                    Operation::Divide => {
-                        if b == 0f64 {
-                            return false;
-                        }
-                        a / b
-                    }
-                };
-                stack.push(result);
-            } else if let Card::Int(num) = t {
-                stack.push(*num as f64);
-            }
-        }
-        if stack.len() != 1 {
-            return false;
-        }
-        (24f64 - stack[0]).abs() < 1e-5
-    }
-    fn dfs(cards: &Vec<i32>, card_objects: &mut Vec<Card>, visited: &mut Vec<bool>) -> bool {
-        if card_objects.len() == 7 {
-            return Self::solve(card_objects);
-        }
-        for i in 0..8 {
-            if i <= 3 {
-                if visited[i] {
-                    continue;
-                }
-                visited[i] = true;
-                card_objects.push(Card::Int(cards[i]));
-                if Self::dfs(cards, card_objects, visited) {
-                    return true;
-                }
-                card_objects.pop();
-                visited[i] = false;
-            }
-            else {
-                let op = match i {
-                    4 => Operation::Add,
-                    5 => Operation::Subtract,
-                    6 => Operation::Multiply,
-                    _ => Operation::Divide,
-                };
-                card_objects.push(Card::Op(op));
-                if Self::dfs(cards, card_objects, visited) {
-                    return true;
-                }
-                card_objects.pop();
-            }
-        }
-        false
-    }
+    pub fn spiral_order(matrix: Vec<Vec<i32>>) -> Vec<i32> {
+        let mut top_x = 0;
+        let mut left_y = 0;
+        let mut bottom_x = matrix.len() as i32 - 1;
+        let mut right_y = matrix[0].len() as i32 - 1;
+        let mut next_x = 0;
+        let mut next_y = 1;
+        let mut pos = (0, 0);
 
-    pub fn judge_point24(cards: Vec<i32>) -> bool {
-        let mut visited = vec![false; 4];
-        let mut card_objects = Vec::new();
-        for i in 0..4 {
-            visited[i] = true;
-            card_objects.push(Card::Int(cards[i]));
-            for j in 0..4 {
-                if visited[j] {
-                    continue;
-                } else {
-                    visited[j] = true;
-                    card_objects.push(Card::Int(cards[j]));
-                    if Self::dfs(&cards, &mut card_objects, &mut visited) {
-                        return true;
+        let mut res = vec![matrix[0][0]];
+
+        let mut next_pos = || {
+            let mut new_pos = (pos.0 + next_x, pos.1 + next_y);
+            if new_pos.0 > bottom_x || new_pos.0 < top_x || new_pos.1 > right_y || new_pos.1 < left_y {
+                (next_x, next_y) = match (next_x, next_y) {
+                    (0, 1) => {
+                        top_x += 1;
+                        (1, 0)
                     }
-                    card_objects.pop();
-                    visited[j] = false;
+                    (1, 0) => {
+                        right_y -= 1;
+                        (0, -1)
+                    }
+                    (0, -1) => {
+                        bottom_x -= 1;
+                        (-1, 0)
+                    }
+                    (-1, 0) => {
+                        left_y += 1;
+                        (0, 1)
+                    }
+                    _ => (0, 0),
+                };
+
+                new_pos = (pos.0 + next_x, pos.1 + next_y);
+                if new_pos.0 > bottom_x
+                    || new_pos.0 < top_x
+                    || new_pos.1 > right_y
+                    || new_pos.1 < left_y
+                {
+                    return false;
                 }
             }
-            card_objects.pop();
-            visited[i] = false;
-        }
-        false
+            pos = new_pos;
+            res.push(matrix[pos.0 as usize][pos.1 as usize]);
+            true
+        };
+        while next_pos() {}
+        res
     }
 }
 
 fn main() {
-    let sl = Solution::judge_point24(vec![3,3,8,8]);
+    let sl = Solution::spiral_order(vec![
+        vec![1, 2, 3, 4],
+        vec![5, 6, 7, 8],
+        vec![9, 10, 11, 12],
+    ]);
     println!("{:?}", sl);
 }