Contribute: Added algorithm and tests for Unique Paths DP problem

Dynamic-Programming/UniquePaths.js

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+/**
+ * A Dynamic Programming based solution for calculating the number ways to travel from Top-Left of the matrix to Bottom-Right of the matrix
+ * https://leetcode.com/problems/unique-paths/
+ */
+
+// Return the number of unique paths, given the dimensions of rows and columns
+
+const uniquePaths = (rows, cols) => {
+  let dp = new Array(cols).fill(1)
+
+  for (let i = 1; i < rows; i++) {
+    const tmp = []
+
+    for (let j = 0; j < cols; j++) {
+      if (j === 0) {
+        tmp[j] = dp[j]
+      } else {
+        tmp[j] = tmp[j - 1] + dp[j]
+      }
+    }
+    dp = tmp
+  }
+  return dp.pop()
+}
+
+export { uniquePaths }

Dynamic-Programming/tests/UniquePaths.test.js

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+import { uniquePaths } from '../UniquePaths'
+
+describe('UniquePaths', () => {
+  it('uniquePaths for rows=3 and cols=7', () => {
+    expect(uniquePaths(3, 7)).toBe(28)
+  })
+
+  it('uniquePaths for rows=3 and cols=2', () => {
+    expect(climbStairs(3, 2)).toBe(3)
+  })
+
+  it('uniquePaths for rows=8 and cols=14', () => {
+    expect(climbStairs(8, 14)).toBe(77520)
+  })
+})