#include <stdio.h>
#include <vector>
// //二分查找（递归）
// bool binary_search(std::vector<int> &sort_array, int begin, int end ,int target){
// if(begin > end){
// return false;
// }
// int mid = (begin+end)/2;
// if(target == sort_array[mid]){
// return true;
// }
// else if(target < sort_array[mid]){
// return binary_search(sort_array, begin, mid-1, target);
// }
// else if(target > sort_array[mid]){
// return binary_search(sort_array, mid+1, end, target);
// }
// }
//二分查找（循环）
bool binary_search(std::vector<int>& sort_array, int target) {
int begin = 0;
int end = sort_array.size() - 1;
while (begin <= end) {
int mid = (begin + end) / 2;
if (target == sort_array[mid]) {
return true;
}
else if (target < sort_array[mid]) {
end = mid - 1;
}
else if (target > sort_array[mid]) {
begin = mid + 1;
}
}
return false;
}
例一：LeetCode35
//给定一个排序数组nums（无重复元素）与目标值target
//如果target在nums中出现，则返回target所在下标，如果target
//在nums中未出现，则返回插入位置下标，使得将target插入nums
//后nums数组任然有序
#include <stdio.h>
#include <vector>
class Solution {
public:
int searchInsert(std::vector<int>& nums, int target) {
int index = -1;
int begin = 0;
int end = nums.size() - 1;
while (index == -1) {
int mid = (begin + end) / 2;
if (target == nums[mid]) {
index = mid;
}
else if (target < nums[mid]) {
if (mid == 0 || target > nums[mid - 1]) {
index = mid;
}
end = mid - 1;
}
else if (target > nums[mid]) {
if (mid == nums.size() - 1 || target < nums[mid + 1]) {
index = mid + 1;
}
begin = mid + 1;
}
}
return index;
}
};
int main() {
int test[] = { 1, 3, 4, 6 };
std::vector<int> nums;
Solution solve;
for (int i = 0; i < 8; i++) {
nums.push_back(test[i]);
}
for (int i = 0; i < 8; i++) {
printf("i = %d index = %d\n", i, solve.searchInsert(nums, i));
}
return 0;
}
例二：LeetCode34
//给定一个排序数组nums（有重复元素）与目标值target
//如果target在nums中出现，则返回target所在区间的左右端点
//下标，如果target在nums中未出现，则返回[-1,-1]
#include <stdio.h>
#include <vector>
class Solution {
public:
std::vector<int> searchRange(std::vector<int>& nums, int target) {
std::vector<int> result;
result.push_back(left_bound(nums, target));
result.push_back(right_bound(nums, target));
return result;
}
private:
int left_bound(std::vector<int>& nums, int target) {
int begin = 0;
int end = nums.size() - 1;
while (begin <= end) {
int mid = (begin + end) / 2;
if (target == nums[mid]) {
if (mid == 0 || nums[mid - 1] < target) {
return mid;
}
end = mid - 1;
}
else if (target < nums[mid]) {
end = mid - 1;
}
else if (target > nums[mid]) {
begin = mid + 1;
}
}
return -1;
}
int right_bound(std::vector<int>& nums, int target) {
int begin = 0;
int end = nums.size() - 1;
while (begin <= end) {
int mid = (begin + end) / 2;
if (target == nums[mid]) {
if (mid == nums.size() - 1 || nums[mid + 1] > target) {
return mid;
}
begin = mid + 1;
}
else if (target < nums[mid]) {
end = mid - 1;
}
else if (target > nums[mid]) {
begin = mid + 1;
}
}
return -1;
}
};
int main() {
int test[] = { 5, 7, 7, 8, 8, 8, 8, 10 };
std::vector<int> nums;
Solution solve;
for (int i = 0; i < 8; i++) {
nums.push_back(test[i]);
}
for (int i = 0; i < 12; i++) {
std::vector<int> result = solve.searchRange(nums, i);
printf("%d : [%d, %d]\n", i, result[0], result[1]);
}
return 0;
}
例三：LeetCode33
/**Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.
(i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).
You are given a target value to search. If found in the array return its index, otherwise return -1.
You may assume no duplicate exists in the array.
Your algorithm's runtime complexity must be in the order of O(log n).
给定要给排序数组nums（nums中无重复元素），且nums可能以
某个未知下标旋转，给定目标值target，求target是否在nums中出现
若出现返回所在下标，未出现返回-1
*/
#include <vector>
#include <stdio.h>
class Solution {
public:
int search(std::vector<int>& nums, int target) {
int begin = 0;
int end = nums.size() - 1;
while (begin <= end) {
int mid = (begin + end) / 2;
if (target == nums[mid]) {
return mid;
}
else if (target < nums[mid]) {
if (nums[begin] < nums[mid]) {
if (target >= nums[begin]) {
end = mid - 1;
}
else {
begin = mid + 1;
}
}
else if (nums[begin] > nums[mid]) {
end = mid - 1;
}
else if (nums[begin] == nums[mid]) {
begin = mid + 1;
}
}
else if (target > nums[mid]) {
if (nums[begin] < nums[mid]) {
begin = mid + 1;
}
else if (nums[begin] > nums[mid]) {
if (target >= nums[begin]) {
end = mid - 1;
}
else {
begin = mid + 1;
}
}
else if (nums[begin] == nums[mid]) {
begin = mid + 1;
}
}
}
return -1;
}
};
int main() {
int test[] = { 9, 12, 15, 20, 1 , 3, 6, 7 };
std::vector<int> nums;
Solution solve;
for (int i = 0; i < 8; i++) {
nums.push_back(test[i]);
}
for (int i = 0; i < 22; i++) {
printf("%d : %d\n", i, solve.search(nums, i));
}
return 0;
}
例四：LeetCode449
//二叉排序树，插入新节点
#include <stdio.h>
#include <vector>
struct TreeNode {
int val;
TreeNode* left;
TreeNode* right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
void BFS_insert(TreeNode* node, TreeNode* insert_node) {
if (insert_node->val < node->val) {
if (node->left) {
BFS_insert(node->left, insert_node);
}
else {
node->left = insert_node;
}
}
else {
if (node->right) {
BFS_insert(node->right, insert_node);
}
else {
node->right = insert_node;
}
}
}
void preorder_print(TreeNode* node, int layer) {
if (!node) {
return;
}
for (int i = 0; i < layer; i++) {
printf("-----");
}
printf("[%d]\n", node->val);
preorder_print(node->left, layer + 1);
preorder_print(node->right, layer + 1);
}
int main() {
TreeNode root(8);
std::vector<TreeNode*> node_vec;
int test[] = { 3, 10, 1, 6, 15 };
for (int i = 0; i < 5; i++) {
node_vec.push_back(new TreeNode(test[i]));
}
for (int i = 0; i < node_vec.size(); i++) {
BFS_insert(&root, node_vec[i]);
}
preorder_print(&root, 0);
for (int i = 0; i < node_vec.size(); i++) {
delete(node_vec[i]);
}
return 0;
}
//二叉查找树查找数值
#include <stdio.h>
#include <vector>
struct TreeNode {
int val;
TreeNode* left;
TreeNode* right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
bool BSF_search(TreeNode* node, int value) {
if (node->val == value) {
return true;
}
if (node->val > value) {
if (node->left) {
return BSF_search(node->left, value);
}
else
return false;
}
else {
if (node->right) {
return BSF_search(node->right, value);
}
else {
return false;
}
}
}
int main() {
TreeNode a(8);
TreeNode b(3);
TreeNode c(10);
TreeNode d(1);
TreeNode e(6);
TreeNode f(15);
a.left = &b;
a.right = &c;
b.left = &d;
b.right = &e;
c.right = &f;
for (int i = 0; i < 20; i++) {
if (BSF_search(&a, i)) {
printf("%d is in the BFS.\n", i);
}
else {
printf("%d is not in the BFS.\n", i);
}
}
return 0;
}
//二叉排序树，插入新节点
#include <stdio.h>
#include <vector>
#include <string>
struct TreeNode {
int val;
TreeNode* left;
TreeNode* right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
//对二叉查找树进行前序遍历， 将遍历得到的节点存储到node_vec中
void collect_nodes(TreeNode* node, std::vector<TreeNode*>& node_vec) {
if (!node) {
return;
}
node_vec.push_back(node);
collect_nodes(node->left, node_vec);
collect_nodes(node->right, node_vec);
}
void BFS_insert(TreeNode* node, TreeNode* insert_node) {
if (insert_node->val < node->val) {
if (node->left) {
BFS_insert(node->left, insert_node);
}
else {
node->left = insert_node;
}
}
else {
if (node->right) {
BFS_insert(node->right, insert_node);
}
else {
node->right = insert_node;
}
}
}
void preorder_print(TreeNode* node, int layer) {
if (!node) {
return;
}
for (int i = 0; i < layer; i++) {
printf("-----");
}
printf("[%d]\n", node->val);
preorder_print(node->left, layer + 1);
preorder_print(node->right, layer + 1);
}
int main() {
TreeNode a(8);
TreeNode b(3);
TreeNode c(10);
TreeNode d(1);
TreeNode e(6);
TreeNode f(15);
a.left = &b;
a.right = &c;
b.left = &d;
b.right = &e;
c.right = &f;
std::vector<TreeNode*> node_vec;
collect_nodes(&a, node_vec);
for (int i = 0; i < node_vec.size(); i++) {
node_vec[i]->left = NULL;
node_vec[i]->right = NULL;
}
for (int i = 1; i < node_vec.size(); i++) {
BFS_insert(node_vec[0], node_vec[i]);
}
preorder_print(node_vec[0], 0);
return 0;
}
/** Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer,
or transmitted across a network connection link to be reconstructed later in the same or another computer environment.
Design an algorithm to serialize and deserialize a binary search tree. There is no restriction on
how your serialization/deserialization algorithm should work. You just need to ensure that a binary search tree can be
serialized to a string and this string can be deserialized to the original tree structure.
The encoded string should be as compact as possible.
Note: Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.
给定一个二叉查找树，实现对该二叉查找树编码与解码功能。
编码即将该二叉查找树转为字符串，解码即将字符串转化为二叉查找树。
不限制使用何种编码算法，只要保证当对二叉树调用编码功能后可再调
用解码功能将其复原。
*/
#include <stdio.h>
#include <vector>
#include <string>
struct TreeNode {
int val;
TreeNode* left;
TreeNode* right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
class Codec {
public:
std::string serialize(TreeNode* root) {
std::string data;
BFS_preorder(root, data);
return data;
}
TreeNode* deserialize(std::string data) {
if (data.length() == 0) {
return NULL;
}
std::vector<TreeNode*> node_vec;
int val = 0;
for (int i = 0; i < data.length(); i++) {
if (data[i] == '#') {
node_vec.push_back(new TreeNode(val));
val = 0;
}
else {
val = val * 10 + data[i] - '0';
}
}
for (int i = 1; i < node_vec.size(); i++) {
BFS_insert(node_vec[0], node_vec[i]);
}
return node_vec[0];
}
private:
void change_int_to_string(int val, std::string& str_val) {
std::string tmp;
while (val) {
tmp += (val % 10) + '0';
val = val / 10;
}
for (int i = tmp.length() - 1; i >= 0; i--) {
str_val += tmp[i];
}
str_val += '#';
}
void BFS_preorder(TreeNode* node, std::string& data) {
if (!node) {
return;
}
std::string str_val;
change_int_to_string(node->val, str_val);
data += str_val;
BFS_preorder(node->left, data);
BFS_preorder(node->right, data);
}
void BFS_insert(TreeNode* node, TreeNode* insert_node) {
if (insert_node->val < node->val) {
if (node->left) {
BFS_insert(node->left, insert_node);
}
else {
node->left = insert_node;
}
}
else {
if (node->right) {
BFS_insert(node->right, insert_node);
}
else {
node->right = insert_node;
}
}
}
};
void preorder_print(TreeNode* node, int layer) {
if (!node) {
return;
}
for (int i = 0; i < layer; i++) {
printf("-----");
}
printf("[%d]\n", node->val);
preorder_print(node->left, layer + 1);
preorder_print(node->right, layer + 1);
}
int main() {
TreeNode a(8);
TreeNode b(3);
TreeNode c(10);
TreeNode d(1);
TreeNode e(6);
TreeNode f(15);
a.left = &b;
a.right = &c;
b.left = &d;
b.right = &e;
c.left = &f;
Codec solve;
std::string data = solve.serialize(&a);
printf("%s\n", data.c_str());
TreeNode* root = solve.deserialize(data);
preorder_print(root, 0);
return 0;
}
例五：LeetCode315
#include <stdio.h>
#include <vector>
//记录左子树数量的而查查找树
struct BSTNode {
int val;
int count;
BSTNode* left;
BSTNode* right;
BSTNode(int x) : val(x), left(NULL), right(NULL), count(0) {}
};
class Solution {
public:
std::vector<int> countSmaller(std::vector<int>& nums) {
std::vector<int> result;
std::vector<BSTNode*> node_vec;
std::vector<int> count;
for (int i = nums.size() - 1; i >= 0; i--) {
node_vec.push_back(new BSTNode(nums[i]));//new 返回的是新 BSTNode 的地址
}
count.push_back(0);
for (int i = 1; i < node_vec.size(); i++) {
int count_small = 0;
BST_insert(node_vec[0], node_vec[i], count_small);
count.push_back(count_small);
}
for (int i = node_vec.size() - 1; i >= 0; i--) {
delete node_vec[i];
result.push_back(count[i]);
}
return result;
}
private:
void BST_insert(BSTNode* node, BSTNode* insert_node, int& count_small) {
if (insert_node->val <= node->val) {
node->count++;
if (node->left) {
BST_insert(node->left, insert_node, count_small);
}
else {
node->left = insert_node;
}
}
else {
count_small += node->count + 1;
if (node->right) {
BST_insert(node->right, insert_node, count_small);
}
else {
node->right = insert_node;
}
}
}
};
int main() {
int test[] = { 5, -7, 9, 1, 3, 5, -2, 1 };
std::vector<int> nums;
for (int i = 0; i < 8; i++) {
nums.push_back(test[i]);
}
Solution solve;
std::vector<int> result = solve.countSmaller(nums);
for (int i = 0; i < result.size(); i++) {
printf("[%d]", result[i]);
}
printf("\n");
return 0;
}
