c/c++语言开发共享洛谷P2312 解方程(暴力)

题意

题目链接

sol

出这种题会被婊死的吧。。。

首先不难想到暴力判断，然后发现连读入都是个问题。

对于(a[i])取模之后再判断就行了。注意判断可能会出现误差，可以多找几个模数

#include<bits/stdc++.h> #define fin(x) {freopen(x, "r", stdin);} #define int long long  using namespace std; const int maxn = 2e5 + 10, mod = 19997; inline int read() {     char c = getchar(); int x = 0, f = 1;     while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}     while(c >= '0' && c <= '9') x = (x * 10 + c - '0') % mod, c = getchar();     return x * f; } int n, m, a[maxn]; int add(int x, int y) {     if(x + y < 0) return x + y + mod;     else return x + y >= mod ? x + y - mod : x + y; } int mul(int x, int y) {     return 1ll * x * y % mod; } int check(int val) {     int now = 0;     for(int i = n; i >= 0; i--) now = mul(now, val), now = add(now, a[i]);     return now == 0; } signed main() {     n = read(); m = read();     for(int i = 0; i <= n; i++) a[i] = read();     int ans = 0; vector<int> out;     for(int i = 1; i <= m; i++) if(check(i)) ans++, out.push_back(i);     printf("%dn", ans);     for(int i = 0; i < out.size(); i++) printf("%dn", out[i]);     return 0; }