leetcode-Largest Number

Given a list of non negative integers, arrange them such that they form the largest number.

For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.

Note: The result may be very large, so you need to return a string instead of an integer.

public class Solution {
    public String largestNumber(int[] num) {
        String result="";
		int length=num.length;
		for(int i=0;i<length;i++){
			int max=num[i];
			int pos=i;
			for(int j=i;j<length;j++){
				if((max+""+num[j]).compareTo(num[j]+""+max)<0){
					max=num[j];
					pos=j;
				}
			}
			if(pos!=i){
				int temp=num[pos];
				num[pos]=num[i];
				num[i]=temp;
			}
		}
		for(int item:num){
			result+=item;
		}
		if(result.startsWith("0"))
			result="0";
		return result;
    }
}

 基本思路：排序，序列为[a,b] 排序的标准是当ab<ba时则两个数字交换。序列变成[b,a]

最后一个判断是防止[0,0] 的序列得出的结果是00.