AcWing 蓝桥杯C++ AB组辅导课 第一讲递归与递推

Posted 2022-02-14 嗯我想想

蓝桥杯C++ AB组辅导课

例题

92. 递归实现指数型枚举

AC代码：

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>

using namespace std;
const int N = 16;

int st[N];
int n;

void dfs(int u) 
    if(u == n) 
        for(int i = 0; i < n; i++)
            if(st[i] == 1)
                printf("%d ",i + 1);
        puts("");
        return;
    
    
    st[u] = 2;
    dfs(u + 1);
    st[u] = 0;
    
    st[u] = 1;
    dfs(u + 1);
    st[u] = 0;
    


int main() 
    
    cin >> n;
    dfs(0);
    
    return 0;

94. 递归实现排列型枚举

AC代码：

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>

using namespace std;
const int N = 10;

int n;
bool used[N];
int way[N];

void dfs(int u) 
    if(u > n) 
        for(int i = 1; i <= n; i++)
            printf("%d ", way[i]);
        puts("");
        return;
    
    
    for(int i = 1; i <= n; i++)
        if(!used[i]) 
            used[i] = true;
            way[u] = i;
            dfs(u + 1);
            used[i] = false;
        



int main() 
    
    cin >> n;
    dfs(1);
    
    return 0;