【leetcode】Largest Number

 1 class Solution {
 2 public:
 3  
 4     static bool cmp(int a,int b)
 5     {
 6         int digitA=1;
 7         int digitB=1;
 8        
 9         int tmpA=a;
10        
11         while(tmpA>=10)
12         {
13             digitA++;
14             tmpA/=10;
15         }
16        
17         int tmpB=b;
18         while(tmpB>=10)
19         {
20             digitB++;
21             tmpB/=10;
22         }
23        
24         return a*pow(10,digitB)+b>b*pow(10,digitA)+a;
25        
26     }
27  
28     string largestNumber(vector<int> &num) {
29        
30         sort(num.begin(),num.end(),cmp);
31        
32         string result="";
33        
34         for(int i=0;i<num.size();i++)  
35         {
36             result+=to_string(num[i]);
37         }
38        
39         if(result[0]==‘0‘) result="0";
40        
41         return result;
42        
43     }
44 };

 1 class Solution {
 2 public:
 3 
 4     static bool cmp(string a,string b)
 5     {
 6         return a+b>b+a;
 7     }
 8 
 9     string largestNumber(vector<int> &num) {
10         
11         int n=num.size();
12         vector<string> strNum(n);
13         for(int i=0;i<n;i++)
14         {
15             strNum[i]=to_string(num[i]);
16         }
17         
18         sort(strNum.begin(),strNum.end(),cmp);
19         
20         string result="";
21         
22         for(int i=0;i<n;i++)
23         {
24             result+=strNum[i];
25         }
26         
27         if(result[0]==‘0‘) result="0";
28         
29         return result;
30     }
31 };