hihocoder57

http://hihocoder.com/contest/offers57/problems
题目1 : 1-偏差排列
DP

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt();
        if(n<=3) {
            System.out.println(n);
            return;
        }
        
        long[]dp=new long[1+n];
        dp[1]=1;
        dp[2]=2;
        for(int i=3;i<=n;i++) dp[i]=dp[i-1]+dp[i-2];
        System.out.println(dp[n]);
    }
}

题目2 : 递增N元组
sort+DP

import java.util.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt(),m=sc.nextInt();
        int[][]a=new int[n][m];
        for(int i=0;i=a[i][j]) continue;
                dp[i][j] = sum[t];
                dp[i][j]%=1000000007;
            }
        }
            
        long s=0;
        for(int j=0;j=v) hi=mid-1;
            else lo=mid;
        }
        if(lo+1==hi && a[hi]

题目3 : 逃离迷宫5
BFS+DP

import java.util.Arrays;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt();
        char[][]cs=new char[n][n];
        for(int i=0;iq=new LinkedList(); //, qq=new LinkedList(), tmp=new LinkedList();
        q.add(new int[]{0,0});
        while(!q.isEmpty()) {
            while(!q.isEmpty()) {
                int[]t=q.remove();
                int i=t[0],j=t[1];
                if(i==n-1&&j==n-1) {
                    System.out.println(Math.min(dp[n-1][n-1][0], dp[n-1][n-1][1]));
                    return;
                }
                
                for(int[]d:dirs) {
                    int ii=t[0]+d[0],jj=t[1]+d[1];
                    if(ii<0||jj<0||ii>=n||jj>=n) continue;
                    if(cs[ii][jj]=='.') {
                        if(dp[i][j][0]+1