1 #include<set>
 2 #include<stack>
 3 #include<queue>
 4 #include<stdio.h>
 5 #include<iostream>
 6 #include<stdlib.h>
 7 #include<string.h>
 8 #include<math.h>
 9 #include<algorithm>
10 #include<map>
11 using namespace std;
12 int main(void)
13 {
14     int i,j,k,p,q;
15     while(scanf("%d %d",&p,&q)!=EOF)
16     {
17         int cc=2*p;
18         int dd=3*q;
19         int yy=max(cc,dd);
20         int flag=0;
21         for(i=yy;; i++)
22         {
23             if(i%2==0||i%3==0)
24             {
25                 int uu=i/2;
26                 int kk=i/3;
27                 int zz=i/6;
28                 int x1=(uu-zz);
29                 int x2=(kk-zz);
30                 x1=p-x1;
31                 x2=q-x2;
32                 if(x1<0)
33                 {
34                     x1=0;
35                 }
36                 if(x2<0)
37                 {
38                     x2=0;
39                 };
40                 if(x1+x2==zz)
41                 {
42                     break;
43                 }
44             }
45         }
46         printf("%d\n",i);
47 
48     }
49 }

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 int er(int n,int m,int a,int b);
 5 using namespace std;
 6 int main()
 7 {
 8     int a,b;
 9     scanf("%d%d",&a,&b);
10     int r=10000000;
11     int k=er(0,r,a,b);
12     printf("%d\n",k);
13     return 0;
14 }
15 
16 int er(int n,int m,int a,int b)
17 {
18     int mid=(n+m)/2;
19     if(n>m)
20     {
21         return n;
22     }
23     int cnt=max(a-mid/2+mid/6,0)+max(b-mid/3+mid/6,0);
24     if(mid/6>=cnt)
25     {
26         return er(n,mid-1,a,b);
27     }
28     else
29         return er(mid+1,m,a,b);
30 }

 1 while(l<=r)
 2     {
 3         int mid=(l+r)>>1;
 4         int ret=max(a-mid/2+mid/6,0)+max(b-mid/3+mid/6,0);
 5         if(mid/6==ret)
 6         {
 7           break;
 8         }else if(mid/6>ret)
 9         {
10             r=mid-1;
11         }
12         else l=mid+1;
13     }