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authorJack Sangdahl <[email protected]>2025-03-10 00:36:13 -0600
committerJack Sangdahl <[email protected]>2025-03-10 00:36:13 -0600
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parent5d7cdc215e4ba1ec4cbb24c084cccb5e5e641468 (diff)
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chore: move cpp and rust code to directory
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+// 688. Knight Probability in Chessboard
+#include "leetcode.h"
+
+/*
+ * on an 'n x n' chessboard, a knight starts at the cell '(row, column)' and
+ * attempts to make exactly 'k' moves. the rows and columns are 0-indexed, so
+ * the top-left cell is '(0, 0)', and the bottom-right cell is '(n - 1, n - 1)'.
+ * a chess knight has eight possible moves it can make, as illustrated below
+ * [see image]. each move is two cells in a cardinal direction, then one cell in
+ * an orthogonal direction.
+ */
+
+class Solution {
+public:
+ double knightProbability(int n, int k, int row, int col) {
+ unordered_map<int, unordered_map<int, unordered_map<int, double>>> dp;
+ if (dp.count(row) && dp[row].count(col) && dp[row][row].count(k))
+ return dp[row][col][k];
+ if (row < 0 || row >= n || col < 0 || col >= n)
+ return 0;
+ if (!k)
+ return 1;
+ double total = knightProbability(n, k - 1, row - 1, col - 2) +
+ knightProbability(n, k - 1, row - 2, col - 1) +
+ knightProbability(n, k - 1, row - 1, col + 2) +
+ knightProbability(n, k - 1, row - 2, col + 1) +
+ knightProbability(n, k - 1, row + 1, col + 2) +
+ knightProbability(n, k - 1, row + 2, col + 1) +
+ knightProbability(n, k - 1, row + 1, col - 2) +
+ knightProbability(n, k - 1, row + 2, col - 1);
+ double ans = total / 8;
+ dp[row][col][k] = ans;
+ return ans;
+ }
+};
+
+int main() {
+ Solution obj;
+ printf("%f\n", obj.knightProbability(3, 2, 0, 0)); // expect: 0.06250
+ printf("%f\n", obj.knightProbability(1, 0, 0, 0)); // expect: 1.00000
+}