前缀和. 设f[i]为前缀和%7=i的第一个点.那么答案就是max(i-f[s[i]%7])了. #include<cstdio> #include<algorithm> #include<cstring> using namespace std; + ; int a[maxn],s[maxn]; ],n,ans; int main() { ;i<;i++) f[i]=-; scanf("%d",&n); ;i<=n;i++) {…

题目大意:给个序列,求最长的连续子序列使其为7的倍数 又是一道令人欢喜的不用怎么用脑的水题.. 边读入,边计算前缀和 分别保存前缀和%7结果为1,2,3,4,5,6的第一次的位置 然后减一减就知道长度啦. #include<stdio.h> #include<string.h> #include<algorithm> using namespace std; ],ans; ]; int main(){ scanf("%d", &n); ans…

Subsequences Summing to Sevens 题目描述 Farmer John's N cows are standing in a row, as they have a tendency to do from time to time. Each cow is labeled with a distinct integer ID number so FJ can tell them apart. FJ would like to take a photo of a conti…

[USACO16JAN]子共七Subsequences Summing to Sevensa[i]表示前缀和如果a[i]%7==t&&a[j]%7==t那么a[j]-a[i-1]一定是7的整数倍,这样就o(n)扫一遍,不断更新答案就可以了. #include<iostream> #include<cstdio> #include<queue> #include<algorithm> #include<cmath> #include…

P3131 [USACO16JAN]子共七Subsequences Summing to Sevens 题目描述 Farmer John's NN cows are standing in a row, as they have a tendency to do from time to time. Each cow is labeled with a distinct integer ID number so FJ can tell them apart. FJ would like to t…

4506: [Usaco2016 Jan]Fort Moo Description Bessie is building a fort with her friend Elsie. Like any good fort, this one needs to start with a sturdy frame. Bessie wants to build a frame in the shape of a one-meter-wide rectangular outline, atop which…

4506: [Usaco2016 Jan]Fort Moo Time Limit: 10 Sec  Memory Limit: 128 MBSubmit: 145  Solved: 104[Submit][Status][Discuss] Description Bessie正在和她的朋友Elsie建一座堡垒.像任何好的堡垒一样,这需要从一个坚固的框架开始.Bessie想要在一 个矩形上建造堡垒,并在矩形周围围上1x1的框架.Bessie已经选择了一个建造堡垒的地方 —— 一块长宽分别为 为NM…

bzoj4512[Usaco2016 Jan] Build Gates 题意: 某人从农场的(0,0)出发,沿边界到处乱走,走过的地方会留下栅栏,等走完后问要在多少个栅栏上开门才能使整个农场连通,最多走1000步. 题解: 我的代码比别人的都长~我的做法是先算出最左/最下可能会走到哪里,然后变换一下坐标系(实际是是改变出发起点),然后记录哪个格子的上下左右被栅栏堵了,最后做一下floodfill,输出连通块数-1.注意还要把有栅栏区域的外圈格子也算进去,因为它们代表了有栅栏区域外的广大地区(这个…

1.题意:给一堆可以的限制长度的区间...区间的长度是你控制的...但是只有一个长度...求最短长度覆盖所有的点 2.分析:发现可以二分...那二分吧.....然后我们从头向后扫一遍直接判断能否直接覆盖...然后就可以AC了<大赛后一水系列> #include <map> #include <set> #include <queue> #include <cmath> #include <cstdio> #include <cs…

二分. #include<cstdio> #include<algorithm> #include<cstring> using namespace std; + ; int n,k,l,r,mid,ans,d; int a[maxn]; bool check(int dist) { dist=*dist; ,sum=; ;i<=n;i++) { ]>dist-d) { sum++; d=; } ]; } //printf("%d %d\n&quo…