CyclicRotation

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problem

solution

option 1

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// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

vector<int> solution(vector<int> &A, int K) {
    // write your code in C++14 (g++ 6.2.0)
    if(A.empty()) return A;
    int n = A.size();
    K %=n;
    vector<int> ret(n,0);
    for(int i=0;i<n;++i) ret[i] = A[(n-K+i)%n];
    return ret;
}

option 2 - reverse

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// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;
#include<algorithm>
vector<int> solution(vector<int> &A, int K) {
    // write your code in C++14 (g++ 6.2.0)

    if(A.empty()) return A;
    int n = A.size();
    K %=n;
    reverse(A.begin(), A.begin()+n-K);
    reverse(A.begin()+n-K, A.end());
    reverse(A.begin(), A.end());
    return A;
}

analysis

  • time complexity O(n)
  • space complexity O(1)