2022.9.17-----leetcode.1624

  public int maxLengthBetweenEqualCharacters(String s) {
        int n=s.length();
        int[] l=new int[26];
        int[] r=new int[26];
        Arrays.fill(l,-1);
        Arrays.fill(r,-1);
        for(int i=0;i<n;i++){
            char c1=s.charAt(i);
            char c2=s.charAt(n-1-i);
            if(l[c1-'a']==-1)
                l[c1-'a']=i;
            if(r[c2-'a']==-1)
                r[c2-'a']=n-1-i;      
        }
        int ans=-1;
        for(int i=0;i<26;i++){
            ans=Math.max(ans,r[i]-l[i]-1);
        }
        return ans;
    }