Update and rename Soltuion.cpp to Solution.cpp

Author: acbin

solution/1300-1399/1307.Verbal Arithmetic Puzzle/Soltuion.cpp

@@ -0,0 +1,103 @@
+class Solution {
+public:
+    bool isAnyMapping(vector<string>& words, int row, int col, int bal, unordered_map<char, int>& letToDig,
+        vector<char>& digToLet, int totalRows, int totalCols) {
+        // If traversed all columns.
+        if (col == totalCols) {
+            return bal == 0;
+        }
+
+        // At the end of a particular column.
+        if (row == totalRows) {
+            return (bal % 10 == 0 && isAnyMapping(words, 0, col + 1, bal / 10, letToDig, digToLet, totalRows, totalCols));
+        }
+
+        string w = words[row];
+
+        // If the current string 'W' has no character in the ('COL')th index.
+        if (col >= w.length()) {
+            return isAnyMapping(words, row + 1, col, bal, letToDig, digToLet, totalRows, totalCols);
+        }
+
+        // Take the current character in the variable letter.
+        char letter = w[w.length() - 1 - col];
+
+        // Create a variable 'SIGN' to check whether we have to add it or subtract it.
+        int sign;
+
+        if (row < totalRows - 1) {
+            sign = 1;
+        } else {
+            sign = -1;
+        }
+
+        /*
+            If we have a prior valid mapping, then use that mapping.
+            The second condition is for the leading zeros.
+        */
+        if (letToDig.count(letter) && (letToDig[letter] != 0 || (letToDig[letter] == 0 && w.length() == 1) || col != w.length() - 1)) {
+
+            return isAnyMapping(words, row + 1, col, bal + sign * letToDig[letter],
+                letToDig, digToLet, totalRows, totalCols);
+
+        }
+        // Choose a new mapping.
+        else {
+            for (int i = 0; i < 10; i++) {
+
+                // If 'i'th mapping is valid then select it.
+                if (digToLet[i] == '-' && (i != 0 || (i == 0 && w.length() == 1) || col != w.length() - 1)) {
+                    digToLet[i] = letter;
+                    letToDig[letter] = i;
+
+                    // Call the function again with the new mapping.
+                    bool x = isAnyMapping(words, row + 1, col, bal + sign * letToDig[letter],
+                        letToDig, digToLet, totalRows, totalCols);
+
+                    if (x == true) {
+                        return true;
+                    }
+
+                    // Unselect the mapping.
+                    digToLet[i] = '-';
+                    if (letToDig.find(letter) != letToDig.end()) {
+                        letToDig.erase(letter);
+                    }
+                }
+            }
+        }
+
+        // If nothing is correct then just return false.
+        return false;
+    }
+
+    bool isSolvable(vector<string>& words, string result) {
+        // Add the string 'RESULT' in the vector 'WORDS'.
+        words.push_back(result);
+
+        int totalRows;
+        int totalCols;
+
+        // Initialize 'TOTALROWS' with the size of the vector.
+        totalRows = words.size();
+
+        // Find the longest string in the vector and set 'TOTALCOLS' with the size of that string.
+        totalCols = 0;
+
+        for (int i = 0; i < words.size(); i++) {
+
+            // If the current string is the longest then update 'TOTALCOLS' with its length.
+            if (totalCols < words[i].size()) {
+                totalCols = words[i].size();
+            }
+        }
+
+        // Create a HashMap for the letter to digit mapping.
+        unordered_map<char, int> letToDig;
+
+        // Create a vector for the digit to letter mapping.
+        vector<char> digToLet(10, '-');
+
+        return isAnyMapping(words, 0, 0, 0, letToDig, digToLet, totalRows, totalCols);
+    }
+};