Spiral matrix ii

Array Matrix Simulation

74.7% acceptance

Jan 12, 2026

6887

287

Given a positive integer n, generate an n x n matrix filled with elements from 1 to n2 in spiral order.

Solution

Rust

Time O(n * m)

Space O(n * m)

LeetCode

solution.rs

impl Solution {
  pub fn generate_matrix(n: i32) -> Vec<Vec<i32>> {
    let n = n as usize;
    let mut matrix = vec![vec![0; n]; n];
    let mut num = 1;
    let mut top = 0;
    let mut bottom = n - 1;
    let mut left = 0;
    let mut right = n - 1;
    
    while top <= bottom && left <= right {
      // Traverse right
      for col in left..=right {
        matrix[top][col] = num;
        num += 1;
      }
      top += 1;
      
      if top > bottom {
        break;
      }
      
      // Traverse down
      for row in top..=bottom {
        matrix[row][right] = num;
        num += 1;
      }
      if right == 0 {
        break;
      }
      right -= 1;
      
      if left > right {
        break;
      }
      
      // Traverse left
      for col in (left..=right).rev() {
        matrix[bottom][col] = num;
        num += 1;
      }
      if bottom == 0 {
        break;
      }
      bottom -= 1;
      
      if top > bottom {
        break;
      }
      
      // Traverse up
      for row in (top..=bottom).rev() {
        matrix[row][left] = num;
        num += 1;
      }
      left += 1;
    }
    
    matrix
  }
}