作业帮3AC（有事，迅速答的，没注意时间复杂度）
第一题
public class zuoyebang1 {
public static void main(String[] args) {int [] arr = {1, 3,5,7,9,11};
zuoyebang1 result = new zuoyebang1();
List<List<Integer>> list = result.getList(arr, 10);
int [][] newArr = new int[list.size()][2];
for(int i = 0; i < list.size(); i++) {
newArr[i][0] = list.get(i).get(0);
newArr[i][1] = list.get(i).get(1);
}
for(int i = 0; i < newArr.length; i++) {
System.out.println(newArr[i][0] + "," + newArr[i][1]);
}
}
private List<List<Integer>> getList(int [] arr, int num) {
List<List<Integer>> result = new ArrayList<>();
if(arr.length == 0) {
return result;
}
int start = 0;
int end = arr.length - 1;
while(start < end) {
if(arr[start] + arr[end] < num) {
start++;
} else if(arr[start] + arr[end] > num) {
end--;
} else {
List<Integer> list = new ArrayList<>();
list.add(arr[start]);
list.add(arr[end]);
result.add(list);
end--;
}
}
return result;
}
}
第二题
public class zuoyebang2 {
public static void main(String[] args) {
zuoyebang2 result = new zuoyebang2();
String str = "I am a student.";
String newString = result.newString(str);
System.out.println(newString);
}
private String newString(String str) {
if(str.trim().equals("")) {
return "";
}
char [] charArr = new char[str.length()];
int index = 0;
for(int i = str.length() - 1; i >= 0; i--) {
charArr[index++] = str.charAt(i);
}
StringBuffer sb = new StringBuffer();
for(int i = 0; i < charArr.length; i++) {
sb.append(charArr[i]);
}
return sb.toString();
}
}
#作业帮##笔试题目##题解#public static void main(String[] args) {
zuoyebang2 result = new zuoyebang2();
String str = "I am a student.";
String newString = result.newString(str);
System.out.println(newString);
}
private String newString(String str) {
if(str.trim().equals("")) {
return "";
}
char [] charArr = new char[str.length()];
int index = 0;
for(int i = str.length() - 1; i >= 0; i--) {
charArr[index++] = str.charAt(i);
}
StringBuffer sb = new StringBuffer();
for(int i = 0; i < charArr.length; i++) {
sb.append(charArr[i]);
}
return sb.toString();
}
}
第三题
public class zuoyebang3 {
public static void main(String[] args) {
int [] arr = {100, 1, 200, 1, 1, 1};
zuoyebang3 result = new zuoyebang3();
int newInt = result.newInt(arr);
System.out.println(newInt);
}
private int newInt(int [] arr) {
if(arr.length == 0) {
return -1;
}
Arrays.sort(arr);
int num = arr[0];
int count = 0;
for(int i = 1; i < arr.length; i++) {
if(num == arr[i] - 1) {
count++;
num = arr[i];
} else if(num == arr[i]) {
count++;
num = arr[i];
} else {
continue;
}
}
if(count > 0) {
return count + 1;
} else {
return count;
}
}
}
public static void main(String[] args) {
int [] arr = {100, 1, 200, 1, 1, 1};
zuoyebang3 result = new zuoyebang3();
int newInt = result.newInt(arr);
System.out.println(newInt);
}
private int newInt(int [] arr) {
if(arr.length == 0) {
return -1;
}
Arrays.sort(arr);
int num = arr[0];
int count = 0;
for(int i = 1; i < arr.length; i++) {
if(num == arr[i] - 1) {
count++;
num = arr[i];
} else if(num == arr[i]) {
count++;
num = arr[i];
} else {
continue;
}
}
if(count > 0) {
return count + 1;
} else {
return count;
}
}
}
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