Initial commit

Medium/valid-sudoku/solution.cpp

@@ -0,0 +1,66 @@
+#include <iostream>
+#include <unordered_map>
+#include <vector>
+
+class Solution {
+  public:
+    /*
+    bool isValidSudoku(std::vector<std::vector<char>> &board) {
+        for (int r = 0; r < 9; ++r) {
+            for (int c = 0; c < 9; ++c) {
+                char num = board[r][c];
+                if (num != '.') {
+                    int count = 0;
+                    for (int i = 0; i < 9; ++i) {
+                        if (num == board[r][i]) {
+                            ++count;
+                        }
+                        if (num == board[i][c]) {
+                            ++count;
+                        }
+                    }
+
+                    int rof = r - r % 3;
+                    int cof = c - c % 3;
+                    for (int i = 0; i < 3; ++i) {
+                        for (int j = 0; j < 3; ++j) {
+                            if (num == board[i + rof][j + cof]) {
+                                ++count;
+                            }
+                        }
+                    }
+
+                    if (count != 3) {
+                        return false;
+                    }
+                }
+            }
+        }
+
+        return true;
+    }
+    */
+
+    bool isValidSudoku(std::vector<std::vector<char>> &board) {
+        std::unordered_map<char, int[9]> count[3];
+
+        for (int i = 0; i < 9; ++i) {
+            for (int j = 0; j < 9; ++j) {
+                char num = board[i][j];
+
+                if (num != '.') {
+                    if (count[0][num][i] != 0 || count[1][num][j] != 0 ||
+                        count[2][num][i / 3 * 3 + j / 3] != 0) {
+                        return false;
+                    }
+
+                    ++count[0][num][i];
+                    ++count[1][num][j];
+                    ++count[2][num][i / 3 * 3 + j / 3];
+                }
+            }
+        }
+
+        return true;
+    }
+};