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Three methods to judge whether it is palindrome structure

2022-07-27 06:43:00 【Xiangxiang baby:】

The first one is （ Transformation type ）

We put the user input int Type data converted to String character string , Then in reverse order , Compare .

pubic static boolean isCircle(int x){
    
	String revX = (new StringBuilder(x + ””).reverse().toString();
	return (x + “”).equals(revx);
}

As for why to use x + ‘’’’,int Data of type +‘’‘’ Can be converted to String Data of type , Remember and get used to

The second kind （ First get the number of digits of the user input value , Find the leftmost and rightmost values , Compare whether the two are the same , If they are the same , Palindrome structure ）

public static boolean isCircle(int x){
    
		//  If the value entered is less than 0, Definitely not palindrome structure 
        if(x < 0){
    
            return false;
        }
        int div = 1;
        // Number of Statistics 
        while(x/div >= 10){
    
            div *= 10;
        }
        // Compare the left and right values one by one 
        while(x > 0){
    
            int left = x /div;
            int right = x % 10;
            if(left != right){
    
                return false;
            }
            x = (x % div)/10;
            div /= 100;
        }
        return true;
    }
}

The third kind of （manacher Algorithm , The algorithm is if it is palindrome structure , There must be the same second half and the first half ）

public static boolean isCircle(int x){
    
	//rex Newly generated data for the second half 
	int rex = 0;
	//div Used for digit transformation 
	int div = 10;
	// Let's experience it here , If the last number is 0, Definitely not palindrome structure （ How can the first number at the beginning be 0？
	if(x == 0 || x%10 == 0 && x != 0 ){
    
		return false;
	}
	//x The reason why it should be greater than rex, Because if it is a number of singular length , Leave the middle number to x Will compare successfully .
	while(x > rex){
    
		rex = res*10 + x%div;
		div *= 10;
	}
	//x == rex/10, Because of x Maybe it's better than rex One less 
	return x == rex || x == rex/10;
}