FrogRiverOne

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problem

solution

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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<unordered_set>
int solution(int X, vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    // 第幾秒落葉會不滿整個[1..X]地方
    unordered_set<int> s;
    int n = A.size();
    for(int i=0;i<n;++i){
        s.insert(A[i]);
        if(s.size()==X) return i;
    }
    return -1;
}

analysis

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