631. Design Excel Sum Formula

src/main/java/algorithms/curated170/hard/DesignExcelSumFormula.java

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+package algorithms.curated170.hard;
+
+import java.util.Arrays;
+
+public class DesignExcelSumFormula {
+
+    class Excel {
+
+        private static final int NO_POS = -1;
+        Object[][] matrix;
+        private final int M, N;
+
+        public Excel(int height, char width) {
+            M = height;
+            N = colIdx(width);
+
+            matrix = new Object[M][N + 1];
+
+            for (int i = 0; i < M; i++) {
+                Arrays.fill(matrix[i], 0);
+            }
+        }
+
+        public void set(int row, char col, int val) {
+            matrix[row - 1][colIdx(col)] = val;
+        }
+
+        public int get(int row, char col) {
+            if (matrix[row - 1][colIdx(col)] instanceof Integer) {
+                return (int) matrix[row - 1][colIdx(col)];
+            } else {
+                return calculate(row, col);
+            }
+        }
+
+        public int sum(int row, char col, String[] numbers) {
+            matrix[row - 1][colIdx(col)] = numbers;
+            return calculate(row, col);
+        }
+
+        public int calculate(int row, char col) {
+            String[] numbers = (String[]) matrix[row - 1][colIdx(col)];
+
+            int sum = 0;
+            for (String num : numbers) {
+                int separatorIdx = num.indexOf(":");
+
+                if (separatorIdx == NO_POS) {
+                    char c = num.charAt(0);
+                    int r = Integer.parseInt(num.substring(1));
+
+                    sum += get(r, c);
+                } else {
+                    sum += sumSubMatrix(num, separatorIdx);
+                }
+            }
+
+            return sum;
+        }
+
+        private int sumSubMatrix(String num, int separatorIdx) {
+            int sum = 0;
+
+            String cell1 = num.substring(0, separatorIdx);
+            String cell2 = num.substring(separatorIdx + 1);
+
+            char c1 = cell1.charAt(0);
+            int r1 = Integer.parseInt(cell1.substring(1));
+
+            char c2 = cell2.charAt(0);
+            int r2 = Integer.parseInt(cell2.substring(1));
+
+            for (int i = r1; i <= r2; i++) {
+                for (char j = c1; j <= c2; j++) {
+                    sum += get(i, j);
+                }
+            }
+            return sum;
+        }
+
+        private int colIdx(char col) {
+            return col - 'A';
+        }
+
+    }
+
+}