add gcd and spiralmatrix

Ajit Singh · Ajit Singh · commit b205c6678d1c · 2018-10-02T18:34:54.000+05:30
diff --git a/math/gcd.js b/math/gcd.js
@@ -0,0 +1,13 @@
+// GCD - greatest common divisor or HCF - highest common factor
+
+function gcd (small, large) {
+  if (small === 0) { return large } else { return gcd(large % small, small) }
+}
+
+const gcdList = [[6, 9], [6, 12], [12, 18], [7, 14], [7, 13]]
+
+for (const set of gcdList) {
+  const small = set[0]
+  const large = set[1]
+  console.log(`GCD for ${small} and ${large} is ${gcd(small, large)}`)
+}
diff --git a/math/spiralMatrix.js b/math/spiralMatrix.js
@@ -0,0 +1,39 @@
+function getSpiralMatrix (n) {
+  const matrix = []
+  for (let i = 0; i < n; ++i) { matrix.push([]) }
+  let counter = 1
+  let startRow = 0
+  let endRow = n - 1
+  let startCol = 0
+  let endCol = n - 1
+
+  while (startCol <= endCol && startRow <= endRow) {
+    for (let i = startCol; i <= endCol; ++i) {
+      matrix[startRow][i] = counter
+      counter++
+    }
+    startRow++
+
+    for (let i = startRow; i <= endRow; ++i) {
+      matrix[i][endCol] = counter
+      counter++
+    }
+    endCol--
+
+    for (let i = endCol; i >= startCol; --i) {
+      matrix[endRow][i] = counter
+      counter++
+    }
+    endRow--
+
+    for (let i = endRow; i >= startRow; --i) {
+      matrix[i][startCol] = counter
+      counter++
+    }
+    startCol++
+  }
+  return matrix
+}
+
+const matrix = getSpiralMatrix(3)
+console.log(matrix)
