剑指Offer之Java算法习题精讲数组与字符串

剑指Offer之Java算法习题精讲数组与字符串

题目一

解法

class Solution {

public int findLengthOfLCIS(int[] nums) {

if(nums.length==1) return 1;

int fast = 1;

int tmp = 1;

int max = Integer.MIN_VALUE;

while(fast

if(nums[fast]>nums[fast-1]){

tmp++;

max = Math.max(max,tmp);

}else{

max = Math.max(max,tmp);

tmp = 1;

}

fast++;

}

return max;

}

}

题目二

解法

class Solution {

public boolean validPalindrome(String s) {

int left = 0;

int right = s.length()-1;

while(left

if(s.charAt(left)==s.charAt(right)){

left++;

right--;

}else{

JwBpPoS String tmp = s.substring(left, right + 1);

return validPalindrome(tmp,1,tmp.length()-1)||validPalindrome(tmp,0,tmp.length()-2);

}

}

JwBpPoS return true;

}

public boolean validPalindrome(String s, int low, int high) {

for (int i = low, j = high; i < j; ++i, --j) {

char c1 = s.charAt(i), c2 = s.charAt(j);

if (c1 != c2) {

return false;

}

}

return true;

}

}

题目三

解法

class Solution {

public double findMaxAverage(int[] nums, int k) {

int w = nums.length-k;

int max = Integer.MIN_VALUE;

for(int i = 0;i<=w;i++){

int res = 0;

for(int j = 0;j

res = nums[i+j]+res;

}

max = Math.max(max,res);

}

double ans = (double)max/k;

return ans;

}

}

题目四

解法

class Solution {

public int findShortestSubArray(int[] nums) {

int[] n = new int[50001];

for(int i = 0;i

n[nums[i]]+=1;

}

int max = Integer.MIN_VALUE;

ArrayList list = new ArrayList();

for(int i = 0;i

max = Math.max(n[i],max);

}

for(int i = 0;i

if(n[i]==max){

list.add(i);

}

}

int min = Integer.MAX_VALUE;

for(int i = 0;i

int res = list.get(i);

int left = 0;

int right = nums.length-1;

while(nums[left]!=res){

left++;

}

while(nums[right]!=res){

right--;

}

min = Math.min(min,right-left+1);

}

return min;

}

}

if(nums[fast]>nums[fast-1]){

tmp++;

max = Math.max(max,tmp);

}else{

max = Math.max(max,tmp);

tmp = 1;

}

fast++;

}

return max;

}

}

题目二

解法

class Solution {

public boolean validPalindrome(String s) {

int left = 0;

int right = s.length()-1;

while(left

if(s.charAt(left)==s.charAt(right)){

left++;

right--;

}else{

JwBpPoS String tmp = s.substring(left, right + 1);

return validPalindrome(tmp,1,tmp.length()-1)||validPalindrome(tmp,0,tmp.length()-2);

}

}

JwBpPoS return true;

}

public boolean validPalindrome(String s, int low, int high) {

for (int i = low, j = high; i < j; ++i, --j) {

char c1 = s.charAt(i), c2 = s.charAt(j);

if (c1 != c2) {

return false;

}

}

return true;

}

}

题目三

解法

class Solution {

public double findMaxAverage(int[] nums, int k) {

int w = nums.length-k;

int max = Integer.MIN_VALUE;

for(int i = 0;i<=w;i++){

int res = 0;

for(int j = 0;j

res = nums[i+j]+res;

}

max = Math.max(max,res);

}

double ans = (double)max/k;

return ans;

}

}

题目四

解法

class Solution {

public int findShortestSubArray(int[] nums) {

int[] n = new int[50001];

for(int i = 0;i

n[nums[i]]+=1;

}

int max = Integer.MIN_VALUE;

ArrayList list = new ArrayList();

for(int i = 0;i

max = Math.max(n[i],max);

}

for(int i = 0;i

if(n[i]==max){

list.add(i);

}

}

int min = Integer.MAX_VALUE;

for(int i = 0;i

int res = list.get(i);

int left = 0;

int right = nums.length-1;

while(nums[left]!=res){

left++;

}

while(nums[right]!=res){

right--;

}

min = Math.min(min,right-left+1);

}

return min;

}

}

if(s.charAt(left)==s.charAt(right)){

left++;

right--;

}else{

JwBpPoS String tmp = s.substring(left, right + 1);

return validPalindrome(tmp,1,tmp.length()-1)||validPalindrome(tmp,0,tmp.length()-2);

}

}

JwBpPoS return true;

}

public boolean validPalindrome(String s, int low, int high) {

for (int i = low, j = high; i < j; ++i, --j) {

char c1 = s.charAt(i), c2 = s.charAt(j);

if (c1 != c2) {

return false;

}

}

return true;

}

}

题目三

解法

class Solution {

public double findMaxAverage(int[] nums, int k) {

int w = nums.length-k;

int max = Integer.MIN_VALUE;

for(int i = 0;i<=w;i++){

int res = 0;

for(int j = 0;j

res = nums[i+j]+res;

}

max = Math.max(max,res);

}

double ans = (double)max/k;

return ans;

}

}

题目四

解法

class Solution {

public int findShortestSubArray(int[] nums) {

int[] n = new int[50001];

for(int i = 0;i

n[nums[i]]+=1;

}

int max = Integer.MIN_VALUE;

ArrayList list = new ArrayList();

for(int i = 0;i

max = Math.max(n[i],max);

}

for(int i = 0;i

if(n[i]==max){

list.add(i);

}

}

int min = Integer.MAX_VALUE;

for(int i = 0;i

int res = list.get(i);

int left = 0;

int right = nums.length-1;

while(nums[left]!=res){

left++;

}

while(nums[right]!=res){

right--;

}

min = Math.min(min,right-left+1);

}

return min;

}

}

res = nums[i+j]+res;

}

max = Math.max(max,res);

}

double ans = (double)max/k;

return ans;

}

}

题目四

解法

class Solution {

public int findShortestSubArray(int[] nums) {

int[] n = new int[50001];

for(int i = 0;i

n[nums[i]]+=1;

}

int max = Integer.MIN_VALUE;

ArrayList list = new ArrayList();

for(int i = 0;i

max = Math.max(n[i],max);

}

for(int i = 0;i

if(n[i]==max){

list.add(i);

}

}

int min = Integer.MAX_VALUE;

for(int i = 0;i

int res = list.get(i);

int left = 0;

int right = nums.length-1;

while(nums[left]!=res){

left++;

}

while(nums[right]!=res){

right--;

}

min = Math.min(min,right-left+1);

}

return min;

}

}

n[nums[i]]+=1;

}

int max = Integer.MIN_VALUE;

ArrayList list = new ArrayList();

for(int i = 0;i

max = Math.max(n[i],max);

}

for(int i = 0;i

if(n[i]==max){

list.add(i);

}

}

int min = Integer.MAX_VALUE;

for(int i = 0;i

int res = list.get(i);

int left = 0;

int right = nums.length-1;

while(nums[left]!=res){

left++;

}

while(nums[right]!=res){

right--;

}

min = Math.min(min,right-left+1);

}

return min;

}

}

max = Math.max(n[i],max);

}

for(int i = 0;i

if(n[i]==max){

list.add(i);

}

}

int min = Integer.MAX_VALUE;

for(int i = 0;i

int res = list.get(i);

int left = 0;

int right = nums.length-1;

while(nums[left]!=res){

left++;

}

while(nums[right]!=res){

right--;

}

min = Math.min(min,right-left+1);

}

return min;

}

}

if(n[i]==max){

list.add(i);

}

}

int min = Integer.MAX_VALUE;

for(int i = 0;i

int res = list.get(i);

int left = 0;

int right = nums.length-1;

while(nums[left]!=res){

left++;

}

while(nums[right]!=res){

right--;

}

min = Math.min(min,right-left+1);

}

return min;

}

}

int res = list.get(i);

int left = 0;

int right = nums.length-1;

while(nums[left]!=res){

left++;

}

while(nums[right]!=res){

right--;

}

min = Math.min(min,right-left+1);

}

return min;

}

}

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