feat(algorithms):62 accepted && testing

Author: guocaoyi

algorithms/0062.unique-paths/index.test.ts

@@ -0,0 +1,72 @@
+import * as asserts from "https://deno.land/std/testing/asserts.ts";
+import * as log from "https://deno.land/std/log/mod.ts";
+import { uniquePaths } from "./index.ts";
+
+log.info("62. Unique Paths");
+
+Deno.test({
+  name: `
+  Input: 3, 2
+  Output: 3
+  `,
+  fn(): void {
+    const result: number = uniquePaths(3, 2);
+    asserts.assertEquals(3, result);
+  },
+});
+
+Deno.test({
+  name: `
+  Input: 7, 3
+  Output: 28
+  `,
+  fn(): void {
+    const result: number = uniquePaths(7, 3);
+    asserts.assertEquals(28, result);
+  },
+});
+
+Deno.test({
+  name: `
+  Input: 3, 3
+  Output: 6
+  `,
+  fn(): void {
+    const result: number = uniquePaths(3, 3);
+    asserts.assertEquals(6, result);
+  },
+});
+
+Deno.test({
+  name: `
+  Input: 1, 1
+  Output: 1
+  `,
+  fn(): void {
+    const result: number = uniquePaths(1, 1);
+    asserts.assertEquals(1, result);
+  },
+});
+
+Deno.test({
+  name: `
+  Input: 2, 3
+  Output: 3
+  `,
+  fn(): void {
+    const result: number = uniquePaths(2, 3);
+    asserts.assertEquals(3, result);
+  },
+});
+
+// 测试 16 * 16 的情况下 Runtime 耗时
+Deno.test({
+  name: `
+  Input: 16, 16
+  Output: 155117520
+  `,
+  fn(): void {
+    const result: number = uniquePaths(16, 16);
+    asserts.assertEquals(155117520, result);
+  },
+});

algorithms/0062.unique-paths/index.ts

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+/**
+ * # 62. Unique Paths
+ *
+ * A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).
+ * 
+ * The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).
+ * 
+ * How many possible unique paths are there?
+ * 
+ * ## Example
+ * 
+ * ```bash
+ * Input: m = 3, n = 2
+ * Output: 3
+ * Explanation:
+ * From the top-left corner, there are a total of 3 ways to reach the bottom-right corner:
+ * 1. Right -> Right -> Down
+ * 2. Right -> Down -> Right
+ * 3. Down -> Right -> Right
+ * ```
+ * ```bash
+ * Input: m = 7, n = 3
+ * Output: 28
+ * ```
+ * 
+ * ## Constraints
+ * 
+ * - `1 <= m, n <= 100`
+ * - It's guaranteed that the answer will be less than or equal to `2 * 10 ^ 9`.
+ */
+export type Solution = (m: number, n: number) => number;
+
+/**
+ * 动态规划
+ * [i,j] -> [m-1,n-1] to [0,0];缓存每个点位的路径数量
+ * @date 2020/07/07 08:47:49
+ * @time O(2n)
+ * @space O(1)
+ * @runtime
+ * @memory
+ * @runtime_cn 72 ms, faster than 75.00%
+ * @memory_cn 35.8 MB, less than 100.00%
+ */
+export const uniquePaths = (m: number, n: number): number => {
+  const arr = new Array(m);
+  for (let i = m - 1; i >= 0; i--) {
+    arr[i] = new Array(n);
+    for (let j = n - 1; j >= 0; j--) {
+      if (i === m - 1 || j === n - 1) {
+        arr[i][j] = 1;
+      } else {
+        arr[i][j] = arr[i + 1][j] + arr[i][j + 1];
+      }
+    }
+  }
+  return arr[0][0];
+};