59 lines
1.4 KiB
Rust
59 lines
1.4 KiB
Rust
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use std::collections::HashMap;
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const CAP: i64 = 1000000007;
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struct DPSolver {
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m: i32,
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n: i32,
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max_move: i32,
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dp: Vec<HashMap<i32, i64>>,
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}
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impl DPSolver {
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pub fn new(m: i32, n: i32, max_move: i32) -> Self {
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let dp = vec![HashMap::new(); (m as usize) * (n as usize)];
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Self { m, n, max_move, dp }
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}
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fn index(&self, y: i32, x: i32) -> usize {
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(y * self.n + x) as usize
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}
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fn dfs(&mut self, y: i32, x: i32, moves: i32) -> i64 {
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if y < 0 || y >= self.m || x < 0 || x >= self.n {
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// BASE: we got out of the bounds
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return 1;
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}
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if moves <= 0 {
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// BASE: all moves were used or there are no moves left
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return 0;
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}
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let idx = self.index(y, x);
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if let Some(paths) = self.dp[idx].get(&moves) {
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return *paths;
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}
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let mut options = 0;
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for (dx, dy) in [(0, 1), (1, 0), (0, -1), (-1, 0)] {
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options = (options + self.dfs(y + dy, x + dx, moves - 1)) % CAP;
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}
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self.dp[idx].insert(moves, options);
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options
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}
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pub fn get(&mut self, y0: i32, x0: i32) -> i32 {
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self.dfs(y0, x0, self.max_move) as i32
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}
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}
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struct Solution {}
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impl Solution {
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pub fn find_paths(m: i32, n: i32, max_move: i32, start_row: i32, start_column: i32) -> i32 {
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DPSolver::new(m, n, max_move).get(start_row, start_column)
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}
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}
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