leetcode 479. Largest Palindrome Product

479. Largest Palindrome Product

注意数值类型！(int) (pro%m)

public class Solution{
	public static void main(String[] args){
		Solution s = new Solution();
		s.largestPalindrome(2);
	}
    public int largestPalindrome(int n) {
    	if(n==1) return 9;
    	//int h = reserve(87);
    	int m = 1337;
    	int mod = (int) Math.pow(10, n);
    	int max = (int) Math.pow(10, n) - 1;
    	long pro = (long)max * (long)max;
    	int left = (int) (pro/mod);
    	int right = (int) (pro%mod);
    	if(left==reserve(right,n)) return (int)(pro%m);
    	if(left>reserve(right,n)) left--;
    	pro = (long)left*(long)mod+ (long)reserve(left,n);
    	while(left!=mod/10){
    		for(int i=max;i>pro/i;i--){
    			if(pro%i==0) return (int) (pro%m);
    		}
    		left--;
    		pro = (long)left*(long)mod+ (long)reserve(left,n);
    	}
    	return (int) (pro%m);
    }
    /*
    private int reserve(int n, int dig){
        int x = n;
        int res = 0;
        int ten = (int)Math.pow(10,dig-1);
        while(x != 0 ){
            int d = x%10;
            res+=ten*d;
            ten/=10;
            x/=10;
        }
        return res;
    }
    */
   
    
	private int reserve(int num, int n) {
		// TODO Auto-generated method stub
		int res =0;
		for(int i=0;i<n;i++){
			int h = num%10;
			res += h*(int)Math.pow(10, n-i-1);
			num = num/10;
		}
		return res;
	}
}