BZOJ1407 [Noi2002]Savage 【扩展欧几里得】

题目链接

题解

枚举\(m\)用扩欧判即可

#include<algorithm>

#include<iostream>

#include<cstring>

#include<cstdio>

#include<cmath>

#define REP(i,n) for (int i = 1; i <= (n); i++)

using namespace std;

const int maxn = 20,maxm = 100005,INF = 1000000000;

inline int read(){

	int out = 0,flag = 1; char c = getchar();

	while (c < 48 || c > 57){if (c == '-') flag = -1; c = getchar();}

	while (c >= 48 && c <= 57){out = (out << 3) + (out << 1) + c - 48; c = getchar();}

	return out * flag;

}

int C[maxn],P[maxn],L[maxn],n;

inline void exgcd(int a,int b,int& d,int& x,int& y){

	if (!b){d = a; x = 1; y = 0;}

	else exgcd(b,a % b,d,y,x),y -= (a / b) * x;

}

inline bool ok(int u,int v,int m){

	int a = P[u] - P[v],b = m,c = C[v] - C[u],d,x,y;

	exgcd(a,b,d,x,y);

	if (c % d) return true;

	b = abs(b / d);

	x = (x * c / d) % b;

	if (x <= 0) x += b;

	return x > min(L[u],L[v]);

}

inline bool check(int m){

	for (register int i = 1; i < n; i++)

		for (register int j = i + 1; j <= n; j++){

			if (!ok(i,j,m)) return false;

		}

	return true;

}

int main(){

	n = read(); int Max = 0;

	bool tag = true;

	REP(i,n){

		C[i] = read(),P[i] = read(),L[i] = read(),Max = max(Max,C[i]);

		C[i]--;

		if (P[i] != 1) tag = false;

	}

	if (tag){printf("%d",Max); return 0;}

	for (register int m = Max; ; m++){

		if (check(m)) {printf("%d\n",m); return 0;}

	}

	return 0;

}

巴特西

BZOJ1407 [Noi2002]Savage 【扩展欧几里得】

题目链接

题解

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