diff options
Diffstat (limited to 'painting_grid_three_colour.cpp')
-rw-r--r-- | painting_grid_three_colour.cpp | 58 |
1 files changed, 0 insertions, 58 deletions
diff --git a/painting_grid_three_colour.cpp b/painting_grid_three_colour.cpp deleted file mode 100644 index 11fb014..0000000 --- a/painting_grid_three_colour.cpp +++ /dev/null @@ -1,58 +0,0 @@ -// 1931. Painting a Grid With Three Different Colors -#include "leetcode.h" - -/* - * given two integers 'm' and 'n'. consider an 'm x n' grid where each cell is - * initially white. you can painteach cell red, green, or blue. all cells must - * be painted. return the number of ways to colour the grid with no two adjacent - * cells having the same colour. - */ - -class Solution { - int memo[1000][1024] = {}; - vector<int> nei_memo[1024] = {}; - int m, n, mod = 1e9 + 7; - int dp(int c, int prev) { - if (c == n) - return 1; - if (memo[c][prev]) - return memo[c][prev]; - int res = 0; - for (int nei : neighbours(prev)) - res = (res + dp(c + 1, nei)) % mod; - return memo[c][prev] = res; - } - vector<int> neighbours(int prev) { - if (!nei_memo[prev].empty()) - return nei_memo[prev]; - dfs(0, prev, 0, nei_memo[prev]); - return nei_memo[prev]; - } - void dfs(int r, int prev, int curr, vector<int> &out) { - if (r == m) { - out.push_back(curr); - return; - } - for (int i = 0; i <= 3; i++) - if (get_colour(prev, r) != i && (!r || get_colour(curr, r - 1) != i)) - dfs(r + 1, prev, set_colour(curr, r, i), out); - } - int get_colour(int mask, int pos) { return (mask >> (2 * pos)) & 3; } - int set_colour(int mask, int pos, int colour) { - return mask | (colour << (2 * pos)); - } - -public: - int colorTheGrid(int m, int n) { - this->m = m; - this->n = n; - return dp(0, 0); - } -}; - -int main() { - Solution obj; - printf("%d\n", obj.colorTheGrid(1, 1)); // expect: 3 - printf("%d\n", obj.colorTheGrid(1, 2)); // expect: 6 - printf("%d\n", obj.colorTheGrid(5, 5)); // expect: 580986 -} |