《Cracking the Coding Interview》——第9章：递归和动态规划——题目4

2014-03-20 03:08

题目：给定一个集合，返回其幂集。

解法：DFS。

代码：

 // 9.4 Return all subsets of a set
 #include <cstdio>
 #include <vector>
 using namespace std;

 void getSubsets(const vector<int> &v, int idx, vector<int> &buffer, vector<vector<int> > &res)
 {
     if (idx == (int)v.size()) {
         res.push_back(buffer);
     } else {
         getSubsets(v, idx + , buffer, res);
         buffer.push_back(v[idx]);
         getSubsets(v, idx + , buffer, res);
         buffer.pop_back();
     }
 }

 int main()
 {
     int i, j;
     vector<vector<int> > res;
     vector<int> v;
     vector<int> buffer;
     int n;

     while (scanf("%d", &n) ==  && n > ) {
         v.resize(n);
         for (i = ; i < n; ++i) {
             scanf("%d", &v[i]);
         }

         getSubsets(v, , buffer, res);

         for (i = ; i < (int)res.size(); ++i) {
             printf("[");
             for (j = ; j < (int)res[i].size(); ++j) {
                 if (j == ) {
                     printf("%d", res[i][j]);
                 } else {
                     printf(" %d", res[i][j]);
                 }
             }
             printf("]\n");
             res[i].clear();
         }
         res.clear();
         buffer.clear();
         v.clear();
     }

     return ;
 }