From 1e65cff7e53e15695e2d5c524489be02060527d1 Mon Sep 17 00:00:00 2001
From: Sainnhe Park <i@sainnhe.dev>
Date: Thu, 24 Nov 2022 17:21:25 +0800
Subject: [PATCH] Remove elements

---
 include/s0283_move_zeroes.hpp | 13 +++++++++++++
 notes/src/SUMMARY.md          |  1 +
 notes/src/remove_elements.md  | 11 +++++++++++
 src/s0027_remove_element.cpp  | 20 ++++++++------------
 src/s0283_move_zeroes.cpp     | 20 ++++++++++++++++++++
 tests/s0283_move_zeroes.cpp   | 19 +++++++++++++++++++
 6 files changed, 72 insertions(+), 12 deletions(-)
 create mode 100644 include/s0283_move_zeroes.hpp
 create mode 100644 notes/src/remove_elements.md
 create mode 100644 src/s0283_move_zeroes.cpp
 create mode 100644 tests/s0283_move_zeroes.cpp

diff --git a/include/s0283_move_zeroes.hpp b/include/s0283_move_zeroes.hpp
new file mode 100644
index 0000000..ce0a36d
--- /dev/null
+++ b/include/s0283_move_zeroes.hpp
@@ -0,0 +1,13 @@
+#ifndef S0283_MOVE_ZEROES_HPP
+#define S0283_MOVE_ZEROES_HPP
+
+#include <vector>
+
+using namespace std;
+
+class Solution {
+ public:
+  void moveZeroes(vector<int>& nums);
+};
+
+#endif
diff --git a/notes/src/SUMMARY.md b/notes/src/SUMMARY.md
index 26fba9d..50acb15 100644
--- a/notes/src/SUMMARY.md
+++ b/notes/src/SUMMARY.md
@@ -1,6 +1,7 @@
 # 数组
 
 - [二分查找](./bin_search.md)
+- [移除元素](./remove_elements.md)
 
 # 经典代码
 
diff --git a/notes/src/remove_elements.md b/notes/src/remove_elements.md
new file mode 100644
index 0000000..90f6c7a
--- /dev/null
+++ b/notes/src/remove_elements.md
@@ -0,0 +1,11 @@
+# 移除元素
+
+查找数组中的目标元素 target ，原地移除该元素，返回移除后的数组长度。
+
+双指针法，快指针用于查找新数组的元素，即不是 target 的元素，慢指针用于覆盖，即写入新数组的元素。
+
+## 相关题目
+
+- [27. 移除元素](https://leetcode.com/problems/remove-element/)
+- [24. 删除排序数组中的重复项](https://leetcode.com/problems/swap-nodes-in-pairs/)
+- [283. 移动零](https://leetcode.com/problems/move-zeroes/)
diff --git a/src/s0027_remove_element.cpp b/src/s0027_remove_element.cpp
index 046a457..71d475a 100644
--- a/src/s0027_remove_element.cpp
+++ b/src/s0027_remove_element.cpp
@@ -1,18 +1,14 @@
 #include "s0027_remove_element.hpp"
 
 int Solution::removeElement(vector<int>& nums, int val) {
-  int size = nums.size();
-  if (size == 0) {
-    return 0;
-  }
-  int fast{0}, slow{0};
-  for (; fast < size; ++fast) {
-    if (nums.at(fast) == val) {
-      continue;
-    } else {
-      nums[slow] = nums.at(fast);
-      ++slow;
+  int len = nums.size();
+  int f{0}, s{0};
+  while (f < len) {
+    if (nums[f] != val) {
+      nums[s] = nums[f];
+      ++s;
     }
+    ++f;
   }
-  return slow;
+  return s;
 }
diff --git a/src/s0283_move_zeroes.cpp b/src/s0283_move_zeroes.cpp
new file mode 100644
index 0000000..3f58eef
--- /dev/null
+++ b/src/s0283_move_zeroes.cpp
@@ -0,0 +1,20 @@
+#include "s0283_move_zeroes.hpp"
+
+void Solution::moveZeroes(vector<int>& nums) {
+  int len = nums.size();
+  if (len <= 1) {
+    return;
+  }
+  int s{0}, f{0};
+  while (f < len) {
+    if (nums[f] != 0) {
+      nums[s] = nums[f];
+      ++s;
+    }
+    ++f;
+  }
+  while (s < len) {
+    nums[s] = 0;
+    ++s;
+  }
+}
diff --git a/tests/s0283_move_zeroes.cpp b/tests/s0283_move_zeroes.cpp
new file mode 100644
index 0000000..346e0ec
--- /dev/null
+++ b/tests/s0283_move_zeroes.cpp
@@ -0,0 +1,19 @@
+#include "s0283_move_zeroes.hpp"
+
+#include <gtest/gtest.h>
+
+TEST(Problem283, Case1) {
+  vector<int> i{0, 1, 0, 3, 12};
+  vector<int> o{1, 3, 12, 0, 0};
+  Solution solution;
+  solution.moveZeroes(i);
+  EXPECT_EQ(i, o);
+}
+
+TEST(Problem283, Case2) {
+  vector<int> i{0};
+  vector<int> o{0};
+  Solution solution;
+  solution.moveZeroes(i);
+  EXPECT_EQ(i, o);
+}