Codeforce937B(暴力)

本文介绍了一个算法问题,目标是在给定区间内找到最大的且不被指定范围内任何数整除的整数。通过逐个检查候选数,确保其满足条件并返回结果。

Vile Grasshoppers

传送门

题意:给你p和y,让你在(p,y]找一个最大的数,这个数不能被[2,p]中的数整除
#include <iostream>
#include <fstream>
#include <cstdio>
#include <cstring>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <cmath>
#include <algorithm>
#include <functional>
#define inf 10000000
using namespace std;
typedef long long ll;
const int MAXN=1e9+10;
const int MAX=1e5+10;
const double eps=1e-6;



int main(){
    #ifdef ONLINE_JUDGE
    #else
    freopen("in.txt","r",stdin);
    //freopen("output.txt","w",stdout);
    #endif

    int p,y;
    cin>>p>>y;
    while(y>p){
        int juge=1;
        for(int i=2;i*i<=y&&i<=p;i++){
            if(y%i==0){
                juge=0;
                break;
            }
        }
        if(juge){
            cout<<y<<endl;
            return 0;
        }
        y--;
    }
    cout<<-1<<endl;

    return 0;
}
### Codeforces Problem 797B Explanation The problem titled "Restoring the Permutation" requires reconstructing a permutation from its prefix sums modulo \( m \). Given an array of integers representing these prefix sums, one must determine whether it is possible to restore such a permutation. In this context, a **permutation** refers to an ordered set containing each integer exactly once within a specified range. The task involves checking if there exists any valid sequence that matches the provided conditions when performing operations as described in the problem statement[^1]. To solve this issue effectively: - Iterate through all elements while maintaining two variables: `current_sum` which tracks cumulative sum during iteration; and `min_value`, used later for adjustments. ```cpp int n, m; cin >> n >> m; vector<int> s(n); for (auto& x : s) cin >> x; ``` Calculate differences between consecutive terms after adjusting initial values appropriately by subtracting minimum value found so far at every step. This adjustment ensures non-negativity throughout calculations without altering relative order among elements. Check feasibility based on properties derived from constraints given in the question text. Specifically, ensure no duplicate residues appear under modulus operation since they would violate uniqueness required for permutations. Finally, construct answer using adjusted difference list obtained previously along with necessary checks ensuring correctness according to rules outlined above.
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