update: 39

Author: hijiangtao

README.md

@@ -30,6 +30,7 @@ This is the solutions collection of my LeetCode submissions, most of them are pr
 |33|[Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/) | [JavaScript](./src/search-in-rotated-sorted-array/res.js)|Medium|
 |34|[Search for a Range](https://leetcode.com/problems/search-for-a-range/) | [JavaScript](./src/search-for-a-range/res.js)|Medium|
 |35|[Search Insert Position](https://leetcode.com/problems/search-insert-position/) | [JavaScript](./src/search-insert-position/res.js)|Easy|
+|39|[Combination Sum](https://leetcode.com/problems/combination-sum/) | [JavaScript](./src/combination-sum/res.js)|Medium|
 |41|[First Missing Positive](https://leetcode.com/problems/first-missing-positive/description/) | [JavaScript](./src/first-missing-positive/res.js)|Hard|
 |42|[	Trapping Rain Water](https://leetcode.com/problems/trapping-rain-water/description/) | [JavaScript](./src/trapping-rain-water/res.js)|Hard|
 |43|[Multiply Strings](https://leetcode.com/problems/multiply-strings/) | [JavaScript](./src/multiply-strings/res.js)|Medium|

src/combination-sum/res.js

@@ -0,0 +1,33 @@
+/**
+ * @param {number[]} candidates
+ * @param {number} target
+ * @return {number[][]}
+ */
+var combinationSum = function(candidates, target) {
+  candidates.sort((a, b) => b-a);
+  const res = [];
+  
+  const calCombs = (candis, resArr, targ) => {
+    if (!candis.length) return ;
+    console.log(candis, resArr, targ);
+    const ele = candis[0];
+
+    if (targ === ele) {
+      res.push([...resArr, ele]);
+    } else {
+      calCombs(candis.slice(1), [...resArr], targ);
+    }
+
+    if (targ - ele > 0) {
+      calCombs(candis, [...resArr, ele], targ-ele);
+    }
+  }
+
+  calCombs(candidates, [], target);
+
+  console.log(res);
+  return res;
+};
+
+combinationSum([2,3,6,7],
+  7);

src/letter-combinations-of-a-phone-number/res.js

@@ -47,4 +47,32 @@ let letterCombinations = function(digits) {
    }
 
    return res;
-};
+};
+
+/**
+ * @param {string} digits
+ * @return {string[]}
+ */
+var letterCombinations_2 = function(digits) {
+    const mapping = ["", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"];
+    const res = [];
+    const len = digits.length;
+    if (len < 1) return [];
+
+    const getCombs = (prefix, start, end) => {
+        const digitMap = mapping[digits[start]];
+        // console.log(prefix, start, end, digitMap);
+        if (start === end) {
+            return digitMap ? digitMap.split('').map(subfix => {
+                return prefix + subfix;
+            }) : [prefix];
+        } else {
+            const subCombs = digitMap ? digitMap.split('').map(subfix => getCombs(prefix+subfix, start + 1, end)) : [getCombs(prefix, start + 1, end)];
+            return subCombs.reduce((acc, cur) => {
+                return acc.concat(cur);
+            }, []);
+        }
+    }
+
+    return res.concat(getCombs('', 0, len-1));
+  };

src/maximum-subarray/res.js

@@ -20,3 +20,14 @@ var maxSubArray = function(nums) {
 
   return ans;
 };
+
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxSubArray = function(nums) {
+  if (nums.length < 1) return 0;
+  
+  return getMaxSum
+};