Lyckades med sudoku-solver

p10957/p10957.cpp

@@ -0,0 +1,158 @@
+#include <algorithm>
+#include <array>
+#include <iostream>
+#include <map>
+#include <utility>
+#include <vector>
+#include <iomanip>
+#include <sstream>
+#include <climits>
+#include <queue>
+#include <list>
+
+using namespace std;
+
+typedef unsigned int nat;
+
+vector<vector<nat>> sudoku(9, vector<nat>(9,0));
+
+void reset_sudoku()
+{
+    for(auto &c : sudoku)
+    {
+        for(auto &cell : c)
+        {
+            cell = 0;
+        }
+    }
+}
+
+bool set_pos(pair<nat,nat> pos, nat val)
+{
+    if(val)
+    {
+        for(auto &c : sudoku)
+        {
+            if(c[pos.second] == val)
+                return false;
+        }
+        for(auto &cell : sudoku[pos.first])
+        {
+            if(cell == val)
+                return false;
+        }
+        for(nat y = 3*(pos.second/3); y < 3*(pos.second/3)+3; ++y)
+        {
+            for(nat x = 3*(pos.first/3); x < 3*(pos.first/3)+3; ++x)
+            {
+                if(sudoku[x][y] == val)
+                    return false;
+            }
+        }
+    }
+
+    sudoku[pos.first][pos.second] = val;
+    return true;
+}
+
+bool get_next(pair<nat,nat> &pos)
+{
+    for(nat y = 0; y < 9; ++y)
+    {
+        for(nat x = 0; x < 9; x++)
+        {
+            if(!sudoku[x][y])
+            {
+                pos = {x,y};
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+void print_sudoku()
+{
+    for(nat y = 0; y < 9; ++y)
+    {
+        for(nat x = 0; x < 9; x++)
+        {
+            cout << sudoku[x][y] << " ";
+        }
+        cout << endl;
+    }
+}
+
+nat solve( )
+{
+    pair<nat,nat> next_cell;
+    nat solutions = 0;
+    if(get_next(next_cell))
+    {
+        bool possible = false;
+        for(nat i = 1; i < 10; ++i)
+        {
+            if(set_pos(next_cell, i))
+            {
+                possible = true;
+                solutions += solve();
+                set_pos(next_cell, 0);
+                if(solutions > 1)
+                    return solutions;
+            }
+        }
+        if(!possible)
+            return 0;
+        else
+            return solutions;
+    }
+    //cout << "One solution is:" << endl;
+    //print_sudoku();
+    return 1;
+}
+
+
+
+int main()
+{
+    nat test_case = 1;
+    while(true)
+    {
+        reset_sudoku();
+        bool success = true;
+        for(nat y = 0; y < 9; ++y)
+        {
+            for(nat x = 0; x < 9; x++)
+            {
+                nat val;
+                cin >> val;
+                if(cin.eof())
+                    return 0;
+
+                success = success && set_pos( {x, y}, val );
+            }
+        }
+
+        cout << "Case " << test_case++ << ": ";
+
+        if(success)
+        {
+            //print_sudoku();
+
+            nat s = solve();
+
+            if(s == 0)
+                cout << "Impossible." << endl;
+            else if(s == 1)
+                cout << "Unique." << endl;
+            else
+                cout << "Ambiguous." << endl;
+        }
+        else
+        {
+            cout << "Illegal." << endl;
+        }
+    }
+    return 0;
+}