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<nums.length){
          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<right){
          if(s.charAt(left)==s.charAt(right)){
              left++;
              right--;
          }else{
              String tmp = s.substring(left, right + 1);
              return validPalindrome(tmp,1,tmp.length()-1)||validPalindrome(tmp,0,tmp.length()-2);
          }
      }
      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<k;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<nums.length;i++){
          n[nums[i]]+=1;
      }
      int max = Integer.MIN_VALUE;
      ArrayList<Integer> list = new ArrayList<Integer>();
      for(int i = 0;i<n.length;i++){
          max = Math.max(n[i],max);
      }
      for(int i = 0;i<n.length;i++){
          if(n[i]==max){
              list.add(i);
          }
      }
      int min = Integer.MAX_VALUE;
      for(int i = 0;i<list.size();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;
  }
}

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原文链接：https://blog.csdn.net/wai_58934/article/details/123282362