Create Soltuion.cpp

Author: CodersAcademy006

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

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+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);
+
+    }
+};