create 0417-pacific-atlantic-water-flow.rs

rust/0417-pacific-atlantic-water-flow.rs

@@ -0,0 +1,66 @@
+use std::collections::HashSet;
+
+impl Solution {
+ pub fn pacific_atlantic(heights: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
+ fn dfs(
+ heights: &Vec<Vec<i32>>,
+ x: i32,
+ y: i32,
+ visit: &mut HashSet<(i32, i32)>,
+ prev: i32,
+ ) {
+ if x < 0
+ || y < 0
+ || x == heights.len() as i32
+ || y == heights[0].len() as i32
+ || heights[x as usize][y as usize] < prev
+ || visit.contains(&(x, y))
+ {
+ return;
+ }
+ visit.insert((x, y));
+ for (add_x, add_y) in [(0, 1), (1, 0), (0, -1), (-1, 0)] {
+ dfs(
+ heights,
+ x + add_x,
+ y + add_y,
+ visit,
+ heights[x as usize][y as usize],
+ );
+ }
+ }
+
+ let (mut pac, mut atl) = (HashSet::new(), HashSet::new());
+ let (n_rows, n_cols) = (heights.len(), heights[0].len());
+
+ for x in 0..n_rows {
+ dfs(&heights, x as i32, 0, &mut pac, heights[x][0]);
+ dfs(
+ &heights,
+ x as i32,
+ n_cols as i32 - 1,
+ &mut atl,
+ heights[x][n_cols - 1],
+ );
+ }
+
+ for y in 0..n_cols {
+ dfs(&heights, 0, y as i32, &mut pac, heights[0][y]);
+ dfs(
+ &heights,
+ n_rows as i32 - 1,
+ y as i32,
+ &mut atl,
+ heights[n_rows - 1][y],
+ );
+ }
+
+ (0..n_rows)
+ .flat_map(|x| (0..n_cols).map(move |y| (x, y)))
+ .filter(|(x, y)| {
+ pac.contains(&(*x as i32, *y as i32)) && atl.contains(&(*x as i32, *y as i32))
+ })
+ .map(|(x, y)| vec![x as i32, y as i32])
+ .collect()
+ }
+}