A1103 Integer Factorization [dfs]
思路:fac[0]=0 fac[1]=1 fac[2]=4…先存fac数组,再对这个数组进行深度优先搜索。
#include<iostream>
#include<vector>
#include<queue>
#include<stack>
#include<string>
#include<math.h>
#include<algorithm>
#include<map>
#include<cstring>
#include<set>
using namespace std;
int n, k, p, maxFacsum = -1;
vector<int>fac, ans, temp;
int power(int x)
{
int ans = 1;
for (int i = 0; i < p; i++)
{
ans *= x;
}
return ans;
}
void init()
{
int i = 0, temp = 0;
while (temp <= n)
{
fac.push_back(temp);
temp = power(++i);
}
}
void dfs(int index, int nowk, int sum, int facsum)
{
if (sum == n && nowk == k)
{
if (facsum > maxFacsum)
{
ans = temp;
maxFacsum = facsum;
}
return;
}
if (sum > n || nowk > k) return;
if (index - 1 >= 0)
{
temp.push_back(index);
dfs(index, nowk + 1, sum + fac[index], facsum + index);
temp.pop_back();
dfs(index - 1, nowk, sum, facsum);
}
}
int main()
{
cin >> n >> k >> p;
init();
dfs(fac.size() - 1, 0, 0, 0);
if (maxFacsum == -1) cout << "Impossible" << endl;
else
{
printf("%d = %d^%d", n, ans[0], p);
for (int i = 1; i < ans.size(); i++)
{
printf(" + %d^%d", ans[i], p);
}
}
return 0;
}