CodeForces 548B

水题一道,却切得很吃力。

题意:n*m的图上有许多小格,小格上是数字0或者1,问每对一个小格上的数字进行反转一次,在所有行中最大的连续的1的个数。

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
struct A
{
  int maxx,sum;
}a[505];
int main()
{
    int n,m,q;
    int s[505][505],maxn,x,y;
    while(scanf("%d%d%d",&n,&m,&q)!=EOF)
    {
      maxn=-1;
      for(int i=1;i<=n;i++)
      for(int j=1;j<=m;j++)
      scanf("%d",&s[i][j]);
      for(int i=1;i<=n;i++)
      {
        a[i].maxx=-1;
        a[i].sum=0;
      }
      for(int i=1;i<=n;i++)
      {
        for(int j=1;j<=m;j++)
        {
          if(s[i][j]==1)
          {
            a[i].sum++;
          }
          else
          {
            a[i].maxx=max(a[i].maxx,a[i].sum);
            a[i].sum=0;
          }
            a[i].maxx=max(a[i].maxx,a[i].sum);
        }
        maxn=max(maxn,a[i].maxx);
      }
      while(q--)
      {
        scanf("%d%d",&x,&y);
        if(s[x][y]==1)
        {
         s[x][y]=0;
        }
        else
        {
         s[x][y]=1;
        }
        a[x].sum=0;
        a[x].maxx=-1;  //!!!
        for(int j=1;j<=m;j++)
        {
         if(s[x][j]==1)
         {
          a[x].sum++;
         }
         else
         {
          a[x].sum=0;
          a[x].maxx=max(a[x].maxx,a[x].sum);
         }
          a[x].maxx=max(a[x].maxx,a[x].sum);
        }
        int ans=-1;
        for(int i = 1; i<=n; i++) //!!!
        ans=max(ans,a[i].maxx);
        printf("%d\n",ans);
      }
    }
    return 0;
}

版权声明:本文为博主原创文章,未经博主允许不得转载。

时间: 2024-10-12 22:07:57

CodeForces 548B的相关文章

CodeForces 548B Mike and Fun (模拟)

题意:给定一个n*m的矩阵,都是01矩阵,然后每次一个询问,改变一个格的值,然后问你最大有数是多少. 析:就是按他说的模拟,要预处理,只要把每行的最大值记下来,当改变时,再更新这一行的最大值. 代码如下: #include<bits/stdc++.h> using namespace std; const int maxn = 500 + 5; int a[maxn][maxn]; int num[maxn]; int main(){ int n, m, q, x, y; while(cin

【codeforces 718E】E. Matvey&#39;s Birthday

题目大意&链接: http://codeforces.com/problemset/problem/718/E 给一个长为n(n<=100 000)的只包含‘a’~‘h’8个字符的字符串s.两个位置i,j(i!=j)存在一条边,当且仅当|i-j|==1或s[i]==s[j].求这个无向图的直径,以及直径数量. 题解:  命题1:任意位置之间距离不会大于15. 证明:对于任意两个位置i,j之间,其所经过每种字符不会超过2个(因为相同字符会连边),所以i,j经过节点至多为16,也就意味着边数至多

Codeforces 124A - The number of positions

题目链接:http://codeforces.com/problemset/problem/124/A Petr stands in line of n people, but he doesn't know exactly which position he occupies. He can say that there are no less than a people standing in front of him and no more than b people standing b

Codeforces 841D Leha and another game about graph - 差分

Leha plays a computer game, where is on each level is given a connected graph with n vertices and m edges. Graph can contain multiple edges, but can not contain self loops. Each vertex has an integer di, which can be equal to 0, 1 or  - 1. To pass th

Codeforces Round #286 (Div. 1) A. Mr. Kitayuta, the Treasure Hunter DP

链接: http://codeforces.com/problemset/problem/506/A 题意: 给出30000个岛,有n个宝石分布在上面,第一步到d位置,每次走的距离与上一步的差距不大于1,问走完一路最多捡到多少块宝石. 题解: 容易想到DP,dp[i][j]表示到达 i 处,现在步长为 j 时最多收集到的财富,转移也不难,cnt[i]表示 i 处的财富. dp[i+step-1] = max(dp[i+step-1],dp[i][j]+cnt[i+step+1]) dp[i+st

Codeforces 772A Voltage Keepsake - 二分答案

You have n devices that you want to use simultaneously. The i-th device uses ai units of power per second. This usage is continuous. That is, in λ seconds, the device will use λ·ai units of power. The i-th device currently has bi units of power store

Educational Codeforces Round 21 G. Anthem of Berland(dp+kmp)

题目链接:Educational Codeforces Round 21 G. Anthem of Berland 题意: 给你两个字符串,第一个字符串包含问号,问号可以变成任意字符串. 问你第一个字符串最多包含多少个第二个字符串. 题解: 考虑dp[i][j],表示当前考虑到第一个串的第i位,已经匹配到第二个字符串的第j位. 这样的话复杂度为26*n*m*O(fail). fail可以用kmp进行预处理,将26个字母全部处理出来,这样复杂度就变成了26*n*m. 状态转移看代码(就是一个kmp

Codeforces Round #408 (Div. 2) B

Description Zane the wizard is going to perform a magic show shuffling the cups. There are n cups, numbered from 1 to n, placed along the x-axis on a table that has m holes on it. More precisely, cup i is on the table at the position x?=?i. The probl

Codeforces 617 E. XOR and Favorite Number

题目链接:http://codeforces.com/problemset/problem/617/E 一看这种区间查询的题目,考虑一下莫队. 如何${O(1)}$的修改和查询呢? 令${f(i,j)}$表示区间${\left [ l,r \right ]}$内数字的异或和. 那么:${f(l,r)=f(1,r)~~xor~~f(1,l-1)=k}$ 记一下前缀异或和即可维护. 1 #include<iostream> 2 #include<cstdio> 3 #include&l