feat(#0115): add Distinct Subsequences

Author: zangbianxuegu

.gitignore

@@ -0,0 +1 @@
+node_modules

0115. Distinct Subsequences.js

@@ -40,9 +40,42 @@
 // babgbag
 //     ^^^
 
+//       b a g
+//     0 1 2 3
+//   0 1 0 0 0
+// b 1 1 1 0 0
+// a 2 1 1 1 0
+// b 3 1 2 1 0
+// g 4 1 2 1 1
+// b 5 1 3 1 1
+// a 6 1 3 4 1
+// g 7 1 3 4 5
+
 /**
  * @param {string} s
  * @param {string} t
  * @return {number}
  */
-const numDistinct = (s, t) => {}
+const numDistinct = (s, t) => {
+  const sLen = s.length
+  const tLen = t.length
+  const dp = [...Array(tLen + 1)].map(() => Array(sLen + 1).fill(0))
+  for (let j = 0; j < sLen; j++) {
+    dp[0][j] = 1
+  }
+  for (let i = 0; i < tLen; i++) {
+    for (let j = 0; j < sLen; j++) {
+      if (t[i] === s[j]) {
+        dp[i + 1][j + 1] = dp[i][j] + dp[i + 1][j]
+      } else {
+        dp[i + 1][j + 1] = dp[i + 1][j]
+      }
+    }
+  }
+  return dp[tLen][sLen]
+}
+
+// test case:
+const s = 'babgbag'
+const t = 'bag'
+console.log(numDistinct(s, t))

package.json

@@ -0,0 +1,53 @@
+{
+  "name": "leetcode",
+  "version": "1.0.0",
+  "description": "记录 LeetCode 解题历程",
+  "main": "leetcode",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "lint": "eslint .",
+    "lint:fix": "eslint . --fix"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/zangbianxuegu/LeetCode.git"
+  },
+  "author": "",
+  "license": "ISC",
+  "bugs": {
+    "url": "https://github.com/zangbianxuegu/LeetCode/issues"
+  },
+  "homepage": "https://github.com/zangbianxuegu/LeetCode#readme",
+  "eslintConfig": {
+    "extends": [
+      "wesbos"
+    ],
+    "rules": {
+      "no-console": 0,
+      "prettier/prettier": [
+        "error",
+        {
+          "semi": false,
+          "trailingComma": "es5",
+          "singleQuote": true,
+          "printWidth": 200,
+          "tabWidth": 2
+        }
+      ]
+    }
+  },
+  "devDependencies": {
+    "babel-eslint": "^9.0.0",
+    "eslint": "^5.16.0",
+    "eslint-config-airbnb": "^17.1.1",
+    "eslint-config-prettier": "^4.3.0",
+    "eslint-config-wesbos": "0.0.19",
+    "eslint-plugin-html": "^5.0.5",
+    "eslint-plugin-import": "^2.20.2",
+    "eslint-plugin-jsx-a11y": "^6.2.3",
+    "eslint-plugin-prettier": "^3.1.3",
+    "eslint-plugin-react": "^7.19.0",
+    "eslint-plugin-react-hooks": "^1.7.0",
+    "prettier": "^1.19.1"
+  }
+}