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240 changes: 117 additions & 123 deletions docs/dataStructures-algorithms/剑指offer部分编程题.md
Original file line number Diff line number Diff line change
Expand Up @@ -14,38 +14,36 @@ n<=39
**采用迭代法:**

```java
int Fibonacci(int number) {
if (number <= 0) {
return 0;
}
if (number == 1 || number == 2) {
return 1;
}
int first = 1, second = 1, third = 0;
for (int i = 3; i <= number; i++) {
third = first + second;
first = second;
second = third;
}
return third;
}
int Fibonacci(int number) {
if (number <= 0) {
return 0;
}
if (number == 1 || number == 2) {
return 1;
}
int first = 1, second = 1, third = 0;
for (int i = 3; i <= number; i++) {
third = first + second;
first = second;
second = third;
}
return third;
}
```

**采用递归:**

```java
public int Fibonacci(int n) {

if (n <= 0) {
return 0;
}
if (n == 1||n==2) {
return 1;
}

return Fibonacci(n - 2) + Fibonacci(n - 1);

}
public int Fibonacci(int n) {
if (n <= 0) {
return 0;
}
if (n == 1||n==2) {
return 1;
}

return Fibonacci(n - 2) + Fibonacci(n - 1);
}
```

### 二 跳台阶问题
Expand All @@ -71,24 +69,24 @@ f(1) = 1, f(2) = 2, f(3) = 3, f(4) = 5, 可以总结出f(n) = f(n-1) + f(n-2)
#### **示例代码:**

```java
int jumpFloor(int number) {
if (number <= 0) {
return 0;
}
if (number == 1) {
return 1;
}
if (number == 2) {
return 2;
}
int first = 1, second = 2, third = 0;
for (int i = 3; i <= number; i++) {
third = first + second;
first = second;
second = third;
}
return third;
}
int jumpFloor(int number) {
if (number <= 0) {
return 0;
}
if (number == 1) {
return 1;
}
if (number == 2) {
return 2;
}
int first = 1, second = 2, third = 0;
for (int i = 3; i <= number; i++) {
third = first + second;
first = second;
second = third;
}
return third;
}
```

### 三 变态跳台阶问题
Expand All @@ -113,9 +111,9 @@ f(n)=f(n-1)+f(n-2)+...+f(1)
#### **示例代码:**

```java
int JumpFloorII(int number) {
return 1 << --number;//2^(number-1)用位移操作进行,更快
}
int JumpFloorII(int number) {
return 1 << --number;//2^(number-1)用位移操作进行,更快
}
```

#### **补充:**
Expand All @@ -124,7 +122,7 @@ f(n)=f(n-1)+f(n-2)+...+f(1)

1. “<<” : **左移运算符**,等同于乘2的n次方
2. “>>”: **右移运算符**,等同于除2的n次方
3. “>>>” **无符号右移运算符**,不管移动前最高位是0还是1,右移后左侧产生的空位部分都以0来填充。与>>类似。
3. “>>>” : **无符号右移运算符**,不管移动前最高位是0还是1,右移后左侧产生的空位部分都以0来填充。与>>类似。
例:
int a = 16;
int b = a << 2;//左移2,等同于16 * 2的2次方,也就是16 * 4
Expand All @@ -147,22 +145,22 @@ f(n)=f(n-1)+f(n-2)+...+f(1)
#### **示例代码:**

```java
public boolean Find(int target, int [][] array) {
//基本思路从左下角开始找,这样速度最快
int row = array.length-1;//行
int column = 0;//列
//当行数大于0,当前列数小于总列数时循环条件成立
while((row >= 0)&& (column< array[0].length)){
if(array[row][column] > target){
row--;
}else if(array[row][column] < target){
column++;
}else{
return true;
}
public boolean Find(int target, int [][] array) {
//基本思路从左下角开始找,这样速度最快
int row = array.length-1;//行
int column = 0;//列
//当行数大于0,当前列数小于总列数时循环条件成立
while((row >= 0)&& (column< array[0].length)){
if(array[row][column] > target){
row--;
}else if(array[row][column] < target){
column++;
}else{
return true;
}
return false;
}
return false;
}
```

### 五 替换空格
Expand All @@ -175,38 +173,37 @@ f(n)=f(n-1)+f(n-2)+...+f(1)

这道题不难,我们可以通过循环判断字符串的字符是否为空格,是的话就利用append()方法添加追加“%20”,否则还是追加原字符。

或者最简单的方法就是利用: replaceAll(String regex,String replacement)方法了,一行代码就可以解决。
或者最简单的方法就是利用:replaceAll(String regex,String replacement)方法了,一行代码就可以解决。

#### **示例代码:**

**常规做法:**

```java
public String replaceSpace(StringBuffer str) {
StringBuffer out=new StringBuffer();
for (int i = 0; i < str.toString().length(); i++) {
char b=str.charAt(i);
if(String.valueOf(b).equals(" ")){
out.append("%20");
}else{
out.append(b);
}
public String replaceSpace(StringBuffer str) {
StringBuffer out = new StringBuffer();
for (int i = 0; i < str.toString().length(); i++) {
char b = str.charAt(i);
if(String.valueOf(b).equals(" ")){
out.append("%20");
}else{
out.append(b);
}
return out.toString();
}
return out.toString();
}
```

**一行代码解决:**

```java
public String replaceSpace(StringBuffer str) {
//return str.toString().replaceAll(" ", "%20");
//public String replaceAll(String regex,String replacement)
//用给定的替换替换与给定的regular expression匹配的此字符串的每个子字符串。
//\ 转义字符. 如果你要使用 "\" 本身, 则应该使用 "\\". String类型中的空格用“\s”表示,所以我这里猜测"\\s"就是代表空格的意思
return str.toString().replaceAll("\\s", "%20");
}

public String replaceSpace(StringBuffer str) {
//return str.toString().replaceAll(" ", "%20");
//public String replaceAll(String regex,String replacement)
//用给定的替换替换与给定的regular expression匹配的此字符串的每个子字符串。
//\ 转义字符. 如果你要使用 "\" 本身, 则应该使用 "\\". String类型中的空格用“\s”表示,所以我这里猜测"\\s"就是代表空格的意思
return str.toString().replaceAll("\\s", "%20");
}
```

### 六 数值的整数次方
Expand Down Expand Up @@ -279,17 +276,17 @@ public class Solution {
当然这一题也可以采用笨方法:累乘。不过这种方法的时间复杂度为O(n),这样没有前一种方法效率高。

```java
// 使用累乘
public double powerAnother(double base, int exponent) {
double result = 1.0;
for (int i = 0; i < Math.abs(exponent); i++) {
result *= base;
}
if (exponent >= 0)
return result;
else
return 1 / result;
// 使用累乘
public double powerAnother(double base, int exponent) {
double result = 1.0;
for (int i = 0; i < Math.abs(exponent); i++) {
result *= base;
}
if (exponent >= 0)
return result;
else
return 1 / result;
}
```

### 七 调整数组顺序使奇数位于偶数前面
Expand Down Expand Up @@ -434,22 +431,21 @@ public class ListNode {
}
}*/
public class Solution {
public ListNode ReverseList(ListNode head) {
ListNode next = null;
ListNode pre = null;
while (head != null) {
//保存要反转到头来的那个节点
next = head.next;
//要反转的那个节点指向已经反转的上一个节点
head.next = pre;
//上一个已经反转到头部的节点
pre = head;
//一直向链表尾走
head = next;
public ListNode ReverseList(ListNode head) {
ListNode next = null;
ListNode pre = null;
while (head != null) {
//保存要反转到头来的那个节点
next = head.next;
//要反转的那个节点指向已经反转的上一个节点
head.next = pre;
//上一个已经反转到头部的节点
pre = head;
//一直向链表尾走
head = next;
}
return pre;
}
return pre;
}

}
```

Expand Down Expand Up @@ -538,20 +534,20 @@ public class Solution {

```java
public ListNode Merge(ListNode list1,ListNode list2) {
if(list1 == null){
return list2;
}
if(list2 == null){
return list1;
}
if(list1.val <= list2.val){
list1.next = Merge(list1.next, list2);
return list1;
}else{
list2.next = Merge(list1, list2.next);
return list2;
}
}
if(list1 == null){
return list2;
}
if(list2 == null){
return list1;
}
if(list1.val <= list2.val){
list1.next = Merge(list1.next, list2);
return list1;
}else{
list2.next = Merge(list1, list2.next);
return list2;
}
}
```

### 十一 用两个栈实现队列
Expand Down Expand Up @@ -642,8 +638,6 @@ https://www.nowcoder.com/questionTerminal/d77d11405cc7470d82554cb392585106
….
依次执行,最后辅助栈为空。如果不为空说明弹出序列不是该栈的弹出顺序。



#### **考察内容:**

Expand Down
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