Merge pull request #29 from rroque98/zeroMatrix

Add JavaScript solution to 1.8 Zero Matrix

Author: fvntr

JavaScript/chapter01/1.8 - Zero Matrix/rroque98_sol.js

@@ -0,0 +1,76 @@
+/*Write an algorithm such that if an element
+ in an M*N matrix is 0,it's entire row and column
+  are set to 0*/
+
+const zeroMatrix = nestedArr => {
+  const rowsAndColsWithZeros = checkForZeroIndex(nestedArr);
+  const rowLength = nestedArr[0].length;
+  const columnLength = nestedArr.length;
+  for (const row in rowsAndColsWithZeros['rows']) {
+    for (let col = 0; col < rowLength; col++) {
+      nestedArr[row][col] = 0;
+    }
+  }
+  for (const col in rowsAndColsWithZeros['columns']) {
+    for (let row = 0; row < columnLength; row++) {
+      nestedArr[row][col] = 0;
+    }
+  }
+  return nestedArr;
+};
+
+// **** Helper function ****
+function checkForZeroIndex(nestArr) {
+  let zeroIndices = { rows: {}, columns: {} };
+  for (let row = 0; row < nestArr.length; row++) {
+    for (let col = 0; col < nestArr[row].length; col++) {
+      if (nestArr[row][col] === 0) {
+        zeroIndices['rows'][row] = true;
+        zeroIndices['columns'][col] = true;
+      }
+    }
+  }
+  return zeroIndices;
+}
+
+// **** TESTS ****:
+let actual = zeroMatrix([[]]);
+let expected = [[]];
+isEqual(actual, expected);
+
+actual = zeroMatrix([[3, 5, 6], [1, 0, 2], [4, 4, 5], [2, 2, 2]]);
+expected = [[3, 0, 6], [0, 0, 0], [4, 0, 5], [2, 0, 2]];
+isEqual(actual, expected);
+
+actual = zeroMatrix([[3, 5, 6], [1, 0, 2], [4, 4, 0], [2, 0, 2]]);
+expected = [[3, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]];
+isEqual(actual, expected);
+
+actual = zeroMatrix([[3, 5, 6], [0, 0, 2], [4, 4, 0], [2, 0, 2]]);
+expected = [[0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0]];
+isEqual(actual, expected);
+
+function isEqual(actual, expected) {
+  console.log(JSON.stringify(actual) === JSON.stringify(expected));
+}
+
+// ****HELPER FUNCTION TESTS ****:
+actual = checkForZeroIndex([[1, 2, 0]]);
+expected = { rows: { 0: true }, columns: { 2: true } };
+testCheckForZeroIndex(actual, expected);
+
+actual = checkForZeroIndex([[0]]);
+expected = { rows: { 0: true }, columns: { 0: true } };
+testCheckForZeroIndex(actual, expected);
+
+actual = checkForZeroIndex([[1, 2, 3], [4, 0, 5], [6, 0, 8]]);
+expected = { rows: { 1: true, 2: true }, columns: { 1: true } };
+testCheckForZeroIndex(actual, expected);
+
+function testCheckForZeroIndex(actual, expected) {
+  let rows = JSON.stringify(actual.rows);
+  let cols = JSON.stringify(actual.columns);
+  let expRows = JSON.stringify(expected.rows);
+  let expCols = JSON.stringify(expected.columns);
+  console.log(rows === expRows && cols === expCols);
+}