first commit

Author: andy6804tw

.gitignore

@@ -0,0 +1,54 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+
+# IDE
+.idea
+
+# OS generated files
+.DS_Store
+.DS_Store?
+._*
+.Spotlight-V100
+ehthumbs.db
+Icon?
+Thumbs.db
+
+# Babel ES6 compiles files
+dist
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (http://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directory
+node_modules
+
+# Optional npm cache directory
+.npm
+
+# Optional REPL history
+.node_repl_history
+
+# .env
+.env
+
+#vs code
+.vscode

Algorithms/C/1-Two-Sum.md

@@ -0,0 +1,34 @@
+# 1-Two Sum
+
+Given an array of integers, return indices of the two numbers such that they add up to a specific target.
+
+You may assume that each input would have exactly one solution, and you may not use the same element twice.
+
+**Example:**
+```
+Given nums = [2, 7, 11, 15], target = 9,
+
+Because nums[0] + nums[1] = 2 + 7 = 9,
+return [0, 1].
+```
+
+- Run Time: 102 ms
+```c
+/**
+ * Note: The returned array must be malloced, assume caller calls free().
+ */
+int *twoSum(int *nums, int numsSize, int target){
+  int i=0,j=0;
+  int *arr=(int *)malloc(2*sizeof(int));
+  for (i=0; i < numsSize;i++){
+    for (j=1+i; j < numsSize;j++){
+      if(nums[i]+nums[j]==target){
+        arr[0]=i;
+        arr[1]=j;
+        return arr;
+      }
+    }
+  }
+  return arr;
+}
+```

Algorithms/C/344-Reverse-String.md

@@ -0,0 +1,33 @@
+# 344-Reverse String
+
+Write a function that takes a string as input and returns the string reversed.
+
+**Example:**
+
+Given s = "hello", return "olleh".
+
+```c
+char* reverseString(char* s) {
+    int i=strlen(s)-1,j=0;
+    char* str=(char*)malloc(strlen(s)+1); 
+    for(;i>=0;i--)
+      str[j++]=s[i];
+    str[i]='\0';
+    return str;
+}
+```
+
+```c
+char* reverseString(char* s) {
+    int i=strlen(s)-1;
+    char* str=(char*)malloc(strlen(s)+1);
+    while(i>=0){
+        *str=s[i--];
+        str++;
+    }
+    *str='\0';
+    str-=strlen(s);
+    
+    return str;
+}
+```

Algorithms/C/a.out

@@ -0,0 +1,27 @@
+#include<stdio.h>
+#include <stdlib.h>
+int *twoSum(int *nums, int numsSize, int target);
+int main()
+{
+  int n[]={1,2,4};
+  int *p = (int *)malloc(2 * sizeof(int));
+  p=twoSum(n, 3, 3);
+  printf("%d",p[0]);
+}
+/**
+ * Note: The returned array must be malloced, assume caller calls free().
+ */
+int *twoSum(int *nums, int numsSize, int target){
+  int i=0,j=0;
+  int *arr=(int *)malloc(2*sizeof(int));
+  for (; i < numsSize;i++){
+    for (; j < numsSize;j++){
+      if(nums[i]+nums[j]==target){
+        arr[0]=i;
+        arr[1]=j;
+        return arr;
+      }
+    }
+  }
+  return arr;
+}

Algorithms/C/test.c

@@ -0,0 +1,64 @@
+# 1-Two Sum
+
+Given an array of integers, return indices of the two numbers such that they add up to a specific target.
+
+You may assume that each input would have exactly one solution, and you may not use the same element twice.
+
+**Example:**
+```
+Given nums = [2, 7, 11, 15], target = 9,
+
+Because nums[0] + nums[1] = 2 + 7 = 9,
+return [0, 1].
+```
+
+##### Solution 1.
+
+此方法最直覺用雙迴圈下去一序做比較
+
+- 暴力、窮舉
+- Run Time:	41 ms
+- 時間複雜度 O(n<sup>2</sup>)
+- 空間複雜度 O(1)
+```java
+class Solution {
+    public int[] twoSum(int[] nums, int target) {
+        for(int i=0;i<nums.length;i++){
+            for(int j=i+1;j<nums.length;j++){
+                if(nums[i]+nums[j]==target){
+                    int arr[]={i,j};
+                    return arr; 
+                }
+            }
+        }
+		return nums;
+    }
+}
+```
+
+##### Solution 2.
+
+
+
+- One-pass Hash Table
+- Run Time:	8 ms
+- 時間複雜度 O(n)
+- 空間複雜度 O(n)
+```java
+class Solution {
+    public int[] twoSum(int[] nums, int target) {
+        Map<Integer,Integer> map=new HashMap<>();
+		int arr[]=new int [2];
+		for(int i=0;i<nums.length;i++) {
+			if(map.containsKey(target-nums[i])) {
+				arr[0]=map.get(target-nums[i]);
+				arr[1]=i;
+				return arr;
+			}else {
+				map.put(nums[i],i);
+			}
+		}
+		return arr;
+    }
+}
+```

Algorithms/Java/1-Two-Sum.md

@@ -0,0 +1,16 @@
+# 344-Reverse String
+
+Write a function that takes a string as input and returns the string reversed.
+
+**Example:**
+
+Given s = "hello", return "olleh".
+
+
+```java
+class Solution {
+    public String reverseString(String s) {
+        return new StringBuffer(s).reverse().toString();
+    }
+}
+```

Algorithms/Java/344-Reverse-String.md

@@ -0,0 +1,5 @@
+# Leetcode
+
+solutions:
+
+ 344. [Reverse String](https://leetcode.com/problems/reverse-string/description/) (Easy)  [C](/Algorithms/C/344-Reverse-String.md) [Java](/Algorithms/Java/344-Reverse-String.md)