Codeforces Round #657 (Div. 2) B. Dubious Cyrpto (思维,数学)

题目传送
题意:
给定l , r , m 。让你求出等式中的a,b,c 。 m = n*a + b - c,其中n是任意的正整数,l <= a,b,c <= r

思路:
既然n是任意的正整数,那么我们直接枚举a的情况,再来判断b-c的情况。

1.先在 l 到 r 的范围枚举a,那么这个时候的b-c有俩种情况
就是n*a 或者 (n+1)*a,但是这里有个坑,就是n必须大于0,所以我们就得先判断(n+1)*a,因为这种情况一定是大于0的

2.那么我们a可以枚举,我们怎么判断b和c呢?
就只用保证,枚举的a去模上m的余数在 r - l 的范围内就可以了,因为b - c的范围就是 r - l 以内

AC代码

#include <bits/stdc++.h>
inline long long read(){char c = getchar();long long x = 0,s = 1;
while(c < '0' || c > '9') {if(c == '-') s = -1;c = getchar();}
while(c >= '0' && c <= '9') {x = x*10 + c -'0';c = getchar();}
return x*s;}
using namespace std;
#define NewNode (TreeNode *)malloc(sizeof(TreeNode))
#define Mem(a,b) memset(a,b,sizeof(a))
#define lowbit(x) (x)&(-x)
const int N = 1e5 + 10;
const long long INFINF = 0x7f7f7f7f7f7f7f;
const int INF = 0x3f3f3f3f;
const double EPS = 1e-7;
const int mod = 1e9+7;
const double II = acos(-1);
const double PP = (II*1.0)/(180.00);
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll,ll> piil;
signed main()
{
    std::ios::sync_with_stdio(false);
    cin.tie(0),cout.tie(0);
    //    freopen("input.txt","r",stdin);
    //    freopen("output.txt","w",stdout);
    int t;
    cin >> t;
    while(t--)
    {
        ll l,r,m,numa,numb,numc;
        cin >> l >> r >> m;
        for(ll i = l;i <= r;i++)
        {
            numa = i;
            if(numa - m % numa <= r-l)
                numc = r,numb = r - (numa - m % numa);
            else
                numb = r,numc = r - m%numa;
            if(numb <= r && numb >= l && numc <= r && numc >= l)
                break;
        }
        cout << numa << " " << numb << " " << numc << endl;
    }
}

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转载自blog.csdn.net/moasad/article/details/107451672