任意门:http://poj.org/problem?id=1320 Street Numbers Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 3181   Accepted: 1776 Description A computer programmer lives in a street with houses numbered consecutively (from 1) down one side of the…

http://poj.org/problem?id=1320 题意很简单,有序列 1,2,3...(a-1),a,(a+1)...b  要使以a为分界的 前缀和 和 后缀和 相等 求a,b 因为序列很特殊所以我们用数学方法就可以解决 : 求和:  a*(a-1)/2 = (a+1+b)(b-a)/2 化简: 2a2  = b2 + b 两边乘4,构造完全平方项 (2b+1)2 - 8a2  = 1 令 x = 2*b+1; y = a; 我们就得到了一个形如Pell方程x2 - Dy2  = 1…

Street Numbers Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 2753   Accepted: 1530 Description A computer programmer lives in a street with houses numbered consecutively (from 1) down one side of the street. Every evening she walks her…

题意:就是从n到1再从1到n的各个数字之和为sum1, 然后从n到m,再从m到n的各个数字之和为sum2,求,(n,m)的前10组解. 思路: 直接建模,利用等差数列的求和公式计算一个公式(2n+1)^2 - m^2=1;   然后直接佩尔方程式即可! #include<cstdio> #include<cmath> #define ll long long int main() { int x, y, x1, y1, px, py; x1 = ; y1 = ; px = ; py…

传送门 Street Numbers Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 2529   Accepted: 1406 Description A computer programmer lives in a street with houses numbered consecutively (from 1) down one side of the street. Every evening she walks…

作弊了--!该题可以通过因式分解得到一个佩尔方程....要不是学着这章,估计想不到.. 得到x1,y1后,就直接代入递推式递推了 x[n]=x[n-1]*x[1]+d*y[n-1]*y[1] y[n]=x[n-1]*y[1]+y[n-1]*x[1] #include <iostream> #include <cstdio> #include <cstring> #include <algorithm> using namespace std; int mai…

Street Numbers Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 3078   Accepted: 1725 Description A computer programmer lives in a street with houses numbered consecutively (from 1) down one side of the street. Every evening she walks her…

hdu2281 输入一个 $N$,求最大的 $n$($n \leq N$)和 $x$,使得 $x^2 = \frac{1^2+2^2+...+n^2}{n}$. 分析: 将右边式子的分子求和化简,有:$x^2 = \frac{(n+1)(2n+1)}{6}$. 变换成:$(4n+3)^2-48x^2 = 1$. 这就是佩尔方程的形式,且样例给出了最小整数解(7, 1). 求出long long范围内的所有解(也就9个) #include<bits/stdc++.h> using namespa…

Log 2016-3-21 网上找的POJ分类,来源已经不清楚了.百度能百度到一大把.贴一份在博客上,鞭策自己刷题,不能偷懒!! 初期: 一.基本算法: (1)枚举. (poj1753,poj2965) (2)贪心(poj1328,poj2109,poj2586) (3)递归和分治法. (4)递推. (5)构造法.(poj3295) (6)模拟法.(poj1068,poj2632,poj1573,poj2993,poj2996) 二.图算法: (1)图的深度优先遍历和广度优先遍历. (2)最短路…

初期:一.基本算法:     (1)枚举. (poj1753,poj2965)     (2)贪心(poj1328,poj2109,poj2586)     (3)递归和分治法.     (4)递推.     (5)构造法.(poj3295)     (6)模拟法.(poj1068,poj2632,poj1573,poj2993,poj2996)二.图算法:     (1)图的深度优先遍历和广度优先遍历.     (2)最短路径算法(dijkstra,bellman-ford,floyd,hea…