add solutions of 4 problems

Author: clingoram

javascript/LeetCode/Array/3190.js

@@ -0,0 +1,20 @@
+/**
+ * 3190. Find Minimum Operations to Make All Elements Divisible by Three
+ * 
+ * 計算能將所有元素被3整除的步驟為幾，一次操作能將元素+1或-1。
+ * 
+ * @param {number[]} nums
+ * @return {number}
+ */
+var minimumOperations = function(nums) {
+  let answer = 0;
+  for(let i = 0;i < nums.length;++i) {
+    if(nums[i] % 3 !== 0){
+      answer++;
+    }
+  }
+  return answer;
+};
+let nums = [1,2,3,4];
+// 3
+console.log(minimumOperations(nums));

javascript/LeetCode/String/28.js

@@ -1,70 +1,17 @@
-
-/**
- * 28. Implement strStr()
- * Difficulty:Easy(459延伸題)
- *
- * Implement strStr().
- *
- * Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
- *
- * Clarification:
- * What should we return when needle is an empty string? This is a great question to ask during an interview.
- * For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C's strstr() and Java's indexOf().
- *
- * ---------------------------------------------------
- * Input: haystack and needle are string
- * Output:在haystack中第一個出現的needle index值
- * 若haystack沒有needle，return -1;
- * 或needle是空的，return 0
- * ------------------------------------------------------
- * Example 1:
- * Input: haystack = "hello", needle = "ll"
- * Output: 2
- *
- * Example 2:
- * Input: haystack = "aaaaa", needle = "bba"
- * Output: -1
- *
- * Example 3:
- * Input: haystack = "", needle = ""
- * Output: 0
- *
- * Constraints:
- * 0 <= haystack.length, needle.length <= 5 * 104
- * haystack and needle consist of only lower-case English characters.
- */
 /**
+ * 28. Find the Index of the First Occurrence in a String
+ 
+ * 回傳needle第一次出現在haystack的index，找不到回傳-1
+ * 
  * @param {string} haystack
  * @param {string} needle
  * @return {number}
  */
-var strStr = function (haystack, needle) {
-  /**
-  * haystack中:
-  * 有needle，return haystack index
-  * 沒有，return -1
-  * $haystack或$needle是空，retunr 0
-  * 
-  * $haystack、$needle 都是英文小寫
-  */
-
-  if (needle === "") {
-    return 0;
-  }
-  for (let i = 0; i < haystack.length; i++) {
-
-    // Return part of string:
-    // for JS: string.substr(start,end)
-    // for PHP: substr(string,start,end)
-    let slice = haystack.substr(i, needle.length);
-    if (slice === needle) {
-      return i;
-    }
-  }
-  return -1;
-
+var strStr = function(haystack, needle) {
+  return haystack.indexOf(needle);
 };
-let h = "hello";
-let nee = "ll";
-// 2
-console.log(strStr(h, nee));
+// let haystack = "leetcode", needle = "leeto";
+// -1
+let haystack = "sadbutsad", needle = "sad";
+// 0
+console.log(strStr(haystack,needle));

javascript/LeetCode/String/58.js

@@ -0,0 +1,34 @@
+/**
+ * 58. Length of Last Word
+ * 
+ * 取得最後一個單字的長度，參數內會有空白格
+ * 
+ * @param {string} s
+ * @return {number}
+ */
+var lengthOfLastWord = function(s) {
+  // solution 1.
+  let temp = [];
+  let splitToArr = s.split(" ");
+  for(let i = 0;i < splitToArr.length;++i) {
+    if(splitToArr[i] !== ""){
+      temp.push(splitToArr[i]);
+    }
+  }
+  return temp[temp.length - 1].length;
+
+  // solution 2.
+//   let ans = 0;
+//   let trim = s.trim();
+//   for(let i = trim.length - 1;i >= 0;i--){
+//     if(trim[i] !== " "){
+//       ans++;
+//     }else if(ans > 0){
+//       break;
+//     }
+//   }
+//   return ans;
+};
+let s = "   fly me   to   the moon  ";
+// 4
+console.log(lengthOfLastWord(s))

javascript/LeetCode/math/9.js

@@ -0,0 +1,17 @@
+/**
+ * 9. Palindrome Number
+ * 
+ * 檢查x是否是迴文（倒著念也一樣）
+ * @param {number} x
+ * @return {boolean}
+ */
+var isPalindrome = function(x) {
+    // 數值不適合顛倒，轉字串
+    let toStr = x.toString().split("").reverse();
+    // console.log(toStr.join(""))
+    
+    return x.toString() === toStr.join("");
+};
+let x = -121;
+// false
+console.log(isPalindrome(x))