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Commit 5f80f94

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Solve #289
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‎src/lib.rs‎

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@@ -218,3 +218,4 @@ mod n0279_perfect_squares;
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mod n0282_expression_add_operators;
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mod n0283_move_zeroes;
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mod n0287_find_the_duplicate_number;
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mod n0289_game_of_life;

‎src/n0289_game_of_life.rs‎

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/**
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* [289] Game of Life
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*
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* According to the <a href="https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life" target="_blank">Wikipedia's article</a>: "The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970."
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*
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* Given a board with m by n cells, each cell has an initial state live (1) or dead (0). Each cell interacts with its <a href="https://en.wikipedia.org/wiki/Moore_neighborhood" target="_blank">eight neighbors</a> (horizontal, vertical, diagonal) using the following four rules (taken from the above Wikipedia article):
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*
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* <ol>
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* Any live cell with fewer than two live neighbors dies, as if caused by under-population.
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* Any live cell with two or three live neighbors lives on to the next generation.
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* Any live cell with more than three live neighbors dies, as if by over-population..
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* Any dead cell with exactly three live neighbors becomes a live cell, as if by reproduction.
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* </ol>
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*
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* Write a function to compute the next state (after one update) of the board given its current state. <span>The next state is created by applying the above rules simultaneously to every cell in the current state, where births and deaths occur simultaneously.</span>
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*
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* Example:
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*
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*
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* Input:
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* <span id="example-input-1-1">[
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* [0,1,0],
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* [0,0,1],
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* [1,1,1],
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* [0,0,0]
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* ]</span>
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* Output:
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* <span id="example-output-1">[
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* [0,0,0],
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* [1,0,1],
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* [0,1,1],
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* [0,1,0]
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* ]</span>
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*
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*
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* Follow up:
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*
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* <ol>
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* Could you solve it in-place? Remember that the board needs to be updated at the same time: You cannot update some cells first and then use their updated values to update other cells.
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* In this question, we represent the board using a 2D array. In principle, the board is infinite, which would cause problems when the active area encroaches the border of the array. How would you address these problems?
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* </ol>
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*
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*/
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pub struct Solution {}
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// submission codes start here
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// in-place: 1: live->live, 0: die->die, 2: die->live, 3: live->die
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impl Solution {
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pub fn game_of_life(board: &mut Vec<Vec<i32>>) {
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let (height, width) = (board.len(), board[0].len());
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let neighbors = vec![(-1,-1),(-1,0),(-1,1),(0,-1),(0,1),(1,-1),(1,0),(1,1)];
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for i in 0..height {
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for j in 0..width {
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let mut live = 0;
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for offset in neighbors.iter() {
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if (offset.0 < 0 && i == 0) ||
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(offset.0 > 0 && i == height -1) ||
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(offset.1 < 0 && j == 0) ||
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(offset.1 > 0 && j == width -1) {
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continue
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}
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let v = board[(i as i32 + offset.0) as usize][(j as i32 + offset.1) as usize];
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if v == 1 || v == 3 {
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live += 1;
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}
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}
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if board[i][j] == 1 && (live < 2 || live > 3) {
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// go die
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board[i][j] = 3;
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} else if board[i][j] == 0 && live == 3 {
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// go live
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board[i][j] = 2;
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}
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}
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}
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for i in 0..height {
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for j in 0..width {
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if board[i][j] == 2 {
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board[i][j] = 1;
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} else if board[i][j] == 3 {
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board[i][j] = 0;
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}
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}
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}
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}
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}
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// submission codes end
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_289() {
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let mut test = vec![
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vec![0,1,0],
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vec![0,0,1],
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vec![1,1,1],
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vec![0,0,0],
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];
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Solution::game_of_life(&mut test);
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assert_eq!(test, vec![
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vec![0,0,0],
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vec![1,0,1],
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vec![0,1,1],
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vec![0,1,0],
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]);
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}
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}

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