LeetCode 179 - Largest Number Leetcode Java

The Code Sniper: 179. Largest Number Leetcode Java

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 String largestNumber(int[] num) {  
     if(num==null || num.length==0) return "";  
     String[] temp=new String[num.length];  
     for(int i=0;i<num.length;i++){  
       temp[i]=String.valueOf(num[i]);  
     }  
     Comparator<String> myComparator=new Comparator<String>(){  
      @Override  
      public int compare(String a, String b){  
        String sa=a+b;  
        String sb=b+a;  
      return sb.compareTo(sa);  
      }  
     };  
     Arrays.sort(temp,myComparator);  
     if(temp[0].equals("0")) return "0";  
     StringBuilder sb=new StringBuilder();  
     for(int i=0;i<temp.length;i++){  
      sb.append(temp[i]);   
     }  
     return sb.toString();  
   }  

http://lixinzhang.github.io/itint5-mian-shi-ti-zong-jie.html

bool cmp(string s1, string s2){
    int size = min(s1.size(), s2.size());
    for(int i=0; i<size; i++){
        if(s1[i] == s2[i]) continue;
        return s1[i] > s2[i];
    }

    if (s1.size() > s2.size()) {
        return cmp(s1.substr(size, s1.size() - size), s2);
    }else if(s1.size() < s2.size()){
        return cmp(s1, s2.substr(size, s2.size() - size));
    }
    /*
    比较函数必须保证是一个全序关系，因此必须有反对称性，
    即若a<b则b<a不成立。你定义的比较函数，对于重合区间a,b， 
    a<b和b<a同时成立，因此sort会core。
    */
    return false;
}


bool cmp2(string s1, string s2){
    //之前的cmp写复杂了，主要保证s1+s2与s2+s1之间的关系即可
    return s1+s2 > s2+s1;
}
string biggestNum(vector<string> &nums) {
    sort(nums.begin(), nums.end(), cmp2);
    string res = "";
    for(unsigned i=0; i<nums.size(); i++){
        res += nums[i];
    }
    return res;

}

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