目录
[牛客. 矩阵最长递增路径](#牛客. 矩阵最长递增路径)
牛客. 矩阵最长递增路径
import java.util.*;
public class Solution {
/**
* 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
*
* 递增路径的最大长度
* @param matrix int整型二维数组 描述矩阵的每个数
* @return int整型
*/
static int []dx={0,0,1,-1};
static int []dy={1,-1,0,0};
static int n;
static int m;
static int[][]dp=new int[10004][1004];
public static int dfs(int[][]matrix,int p1,int p2){
int len=1;
if(dp[p1][p2]!=0){
return dp[p1][p2];
}
for(int i=0;i<4;i++){
int x=p1+dx[i];
int y=p2+dy[i];
if(x>=0&&x<n&&y>=0&&y<m&&matrix[x][y]<matrix[p1][p2]){
len=Math.max(len,dfs(matrix,x,y)+1);
}
}
dp[p1][p2]=len;
return len;
}
public int solve (int[][] matrix) {
int ret=0;
n=matrix.length;
m=matrix[0].length;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
ret=Math.max(ret,dfs(matrix,i,j));
}
}
return ret;
}
}
牛客.奇数位丢弃
import java.util.Scanner;
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
// 注意 hasNext 和 hasNextLine 的区别
while (in.hasNextInt()) { // 注意 while 处理多个 case
int n = in.nextInt();
int ret=1;
//找到所有2^x-1最大的时候
while(ret-1<=n) ret*=2;
//在最后ret是等于>n的2^x次幂,我们需要把这个幂,进行除2,然后-1,因为ret代表的是2^x
System.out.println(ret/2-1);
}
}
}
牛客.天使果冻
假如说问一遍,我们就排序一遍,那么耗费时间度就是n*q
这样是会超时的,所以预处理
采用g[i]:来存这个某一个位置的次大值
那么下次问,就是O(q)了。
如何在一堆数字中,求出第二大/小的值
f[i]来表示当前位置的最大值
import java.util.*; public class Main{ public static void main(String[]args){ Scanner in=new Scanner(System.in); int n=in.nextInt(); int[]a=new int[n]; for(int i=0;i<n;i++){ a[i]=in.nextInt(); } int q=in.nextInt(); int []f=new int[n]; int []g=new int[n]; f[0]=a[0]; //注意初始化,最大值,以及次大值,最大值默认第一个有数字就行 //次大值只有一个数字,没有次大值,无穷小,默认为0; for(int i=1;i<n;i++){ f[i]=Math.max(f[i-1],a[i]); if(a[i]>=f[i-1]){ g[i]=f[i-1]; }else if( a[i]<f[i-1]&&a[i]>=g[i-1]){ g[i]=a[i]; }else{ g[i]=g[i-1]; } } while(q>0){ int x=in.nextInt(); System.out.println(g[x-1]); q--; } } }
牛客.dd爱旋转
一定是模拟,但是开始的时候,我没想到怎么做
这么做,+快速读写
import java.util.*;
import java.io.*;
public class Main{
public static PrintWriter out=new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
public static Read in=new Read();
public static void main(String[]args) throws IOException{
int n = in.nextInt();
int[][] a = new int[n][n];
Stack<Integer> s = new Stack<>();
Queue<Integer> qlist = new LinkedList<>();
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
a[i][j] = in.nextInt();
s.add(a[i][j]);
}
}
int q = in.nextInt();
int count1 = 0;
int count2 = 0;
while (q != 0) {
int x = in.nextInt();
if (x == 1) {
count1++;
}//当他等于2的时候
else {
count2++;
}
q--;
}
if (count1 % 2 != 0) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
a[i][j] = s.pop();
}
}
}
if (count2 % 2 != 0) {
for (int i = n - 1; i >= 0; i--) {
for (int j = 0; j < n; j++) {
qlist.add(a[i][j]);
}
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
a[i][j] = qlist.poll();
}
}
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
out.print(a[i][j] + " ");
}
out.println("");
}
out.close();
}
}
class Read{
StringTokenizer st=new StringTokenizer("");
BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
String next()throws IOException{
while(!st.hasMoreTokens()){
st=new StringTokenizer(bf.readLine());
}
return st.nextToken();
}
int nextInt() throws IOException{
return Integer.parseInt(next());
}
}
上面和下面的换
import java.util.*; import java.io.*; public class Main{ public static PrintWriter out=new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out))); public static Read in=new Read(); static int[][]a; static int n=0; static void setRow(){ for(int i=0; i<n/2;i++){ for(int j=0;j<n;j++){ //行交换 int tmp=a[i][j]; a[i][j]=a[n-1-i][j]; a[n-1-i][j]=tmp; } } } static void setCol(){ //列交换 for(int j=0;j<n/2;j++){ for(int i=0;i<n;i++){ //行不变,列变成n-1-j int tmp=a[i][j]; a[i][j]=a[i][n-1-j]; a[i][n-1-j]=tmp; } } } public static void main(String[]args) throws IOException{ n = in.nextInt(); a = new int[n][n]; Stack<Integer> s = new Stack<>(); Queue<Integer> qlist = new LinkedList<>(); for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { a[i][j] = in.nextInt(); } } int q = in.nextInt(); int row = 0; int col = 0; while (q != 0) { int x = in.nextInt(); if (x == 1) { row++; col++; }//当他等于2的时候 else { row++; } q--; } if (row % 2 != 0) { setRow(); } if (col % 2 != 0) { setCol(); } for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { out.print(a[i][j] + " "); } out.println(""); } out.close(); } } class Read{ StringTokenizer st=new StringTokenizer(""); BufferedReader bf=new BufferedReader(new InputStreamReader(System.in)); String next()throws IOException{ while(!st.hasMoreTokens()){ st=new StringTokenizer(bf.readLine()); } return st.nextToken(); } int nextInt() throws IOException{ return Integer.parseInt(next()); } }