full permutation with backtracking

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字数统计: 148阅读时长: 1 min

 2021/01/14   Share

1, 2, 3 full permutation example in conventional “for circle” full permutation.

with vector path.

then backtracking method.

#include <iostream>
#include <vector>
using namespace std;
void fun(int level, vector<int>&path ){
    if(level == path.size()){
        for(int num:path){
            cout<<num<<" ";
        }
        cout <<endl;
        return;
    }
    for(path[level] = 1; path[level] <= path.size(); path[level]++){
        // before enter into next layer decision tree,
        // checking whether path contains item contained or not.
        // std::count: Returns the number of elements in the range [first,last) that compare equal to val.
        if( count(path.begin(), begin(path) + level, path[level] ) != 0 ) continue;
        fun(level+1, path);
    }
}
int main() {
    vector<int> path(4);
    fun(0, path);
    return 0;
}

reference: https://www.youtube.com/watch?v=nrHTtjkYEyQ

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