事實上只有495種可能的輸入租漂，這其中有404種能計算出24點．
所有可能的輸入：
total = ABCD+AAAA+AAAB+AABB+AABC
total = Ｃ(9,4)+C(9,1)+A(9,2)+C(9,2)+(987)/2
算出total =504;
窮舉所有的total組合并判斷是否能算出24點：
#include <iostream>
#include <unistd.h>
#include <string>
#include <vector>
#include <map>
#include <stack>
#include <algorithm>
#include <math.h>
#include <string.h>
using namespace std;
int counter=0,total=0;
double eps = 0.0000001;
map<vector<int>,int> table;
class Solution {
public:
bool solution(double a,double b)
{
return fabs(a+b-24)<eps||fabs(a-b-24)<eps||fabs(a*b-24)<eps||b&&fabs(a/b-24)<eps;
}
bool solution(double a,double b,double c)
{
bool f1 = solution(a+b,c)||solution(a-b,c)||solution(a*b,c)||b&&solution(a/b,c);
bool f2 = solution(a,b+c)||solution(a,b-c)||solution(a,b*c)||c&&solution(a,b/c);
return f1||f2;
}
bool solution(vector<int>& nums)
{
double a = nums[0],b = nums[1],c = nums[2],d = nums[3];
bool f1 = solution(a+b,c,d)||solution(a-b,c,d)||solution(a*b,c,d)||solution(a/b,c,d);
bool f2 = solution(a,b+c,d)||solution(a,b-c,d)||solution(a,b*c,d)||solution(a,b/c,d);
bool f3 = solution(a,b,c+d)||solution(a,b,c-d)||solution(a,b,c*d)||solution(a,b,c/d);
return f1||f2||f3;
}
bool judgePoint24(vector<int>& nums) {
sort(nums.begin(),nums.end());
do{
if(solution(nums))
{
for(int i=0;i<nums.size();i++)
{
cout<<nums[i]<<" ";
}
cout<<endl;
counter++;
return true;
}
}while(next_permutation(nums.begin(),nums.end()));
return false;
}
};
int main()
{
Solution s1;
for(int i=1;i<=9;i++)
{
for(int j=i+1;j<=9;j++)
{
for(int k=j+1;k<=9;k++)
{
for(int p=k+1;p<=9;p++)
{
vector<int> nums(4);
nums[0]=i;nums[1]=j;nums[2]=k;nums[3]=p;
s1.judgePoint24(nums);
total++;
}
}
}
}
for(int i=1;i<=9;i++)
{
for(int j=1;j<=9;j++)
{
for(int k=j+1;k<=9;k++)
{
vector<int> nums(4);
if(j!=i&&k!=i&&k!=j)
{
nums[0]=i;nums[1]=i;nums[2]=j;nums[3]=k;
s1.judgePoint24(nums);
total++;
}
}
}
}
for(int i=1;i<=9;i++)
{
vector<int> nums(4);
nums[0]=i;nums[1]=i;nums[2]=i;nums[3]=i;
s1.judgePoint24(nums);
total++;
for(int j=i+1;j<=9;j++)
{
nums[0]=i;nums[1]=i;nums[2]=i;nums[3]=j;
s1.judgePoint24(nums);
total++;
nums[0]=i;nums[1]=j;nums[2]=j;nums[3]=j;
s1.judgePoint24(nums);
total++;
}
}
for(int i=1;i<=9;i++)
{
vector<int> nums(4);
for(int j=i+1;j<=9;j++)
{
nums[0]=i;nums[1]=i;nums[2]=j;nums[3]=j;
s1.judgePoint24(nums);
total++;
}
}
cout<<"counter = "<<counter<<endl;
cout<<"total = "<<total<<endl;
}
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