44 lines
1.7 KiB
C++
44 lines
1.7 KiB
C++
#include <vector>
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/**
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* 289. Game of Life
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* According to Wikipedia's article: "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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* The board is made up of an m x n grid of cells, where each cell has an initial state: live (represented by a 1) or dead (represented by a 0). Each cell interacts with its eight neighbors (horizontal, vertical, diagonal) using the following four rules (taken from the above Wikipedia article):
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*
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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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* The next state is created by applying the above rules simultaneously to every cell in the current state, where births and deaths occur simultaneously. Given the current state of the m x n grid board, return the next state.
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*/
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class Solution {
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public:
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static void gameOfLife(std::vector<std::vector<int>>& board) {
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int m = board.size(), n = board.front().size();
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auto GetIfValid = [&](int x, int y) {
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return (x >= 0 && y >= 0 && x < m && y < n) ? board[x][y] & 1 : 0;
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};
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for (int i = 0; i < m; ++i) {
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for (int j = 0; j < n; ++j) {
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int c = -board[i][j];
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for (int di = -1; di <= 1; ++di)
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for (int dj = -1; dj <= 1; ++dj)
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c += GetIfValid(i + di, j + dj);
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switch (c) {
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case 2:
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if (!(board[i][j] & 1))
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break;
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case 3:
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board[i][j] |= 2;
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default:;
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}
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}
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}
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for (auto& i : board)
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for (auto& j : i)
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j >>= 1;
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}
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};
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