【算法系列学习】[kuangbin带你飞]专题十二 基础DP1 G

https://vjudge.net/contest/68966#problem/G

正解一：

http://www.clanfei.com/2012/04/646.html

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<cmath>
#define INF 0x3f3f3f3f
using namespace std;
const int maxn=1e5+1;
int a[11][maxn];
int dp[11][maxn];

bool check(int x)
{
    if(x>=0&&x<=10)
    {
        return 1;
    }
    return 0;
}
int main()
{
    int n,x,y,maxtime;
    while(scanf("%d",&n)==1&&n)
    {
        maxtime=-INF;
        memset(a,0,sizeof(a));
        for(int i=0;i<n;i++)
        {
            scanf("%d%d",&x,&y);
            a[x][y]++;
            maxtime=max(maxtime,y);
        }
        memset(dp,0,sizeof(dp));
        for(int i=maxtime-1;i>=0;i--)
        {
            for(int k=0;k<=10;k++)
            {
                dp[k][i]=dp[k][i+1];
                if(check(k-1))
                {
                    dp[k][i]=max(dp[k][i],dp[k-1][i+1]);
                }
                if(check(k+1))
                {
                    dp[k][i]=max(dp[k][i],dp[k+1][i+1]);
                }
                dp[k][i]+=a[k][i];
            }
        }
        printf("%d
",dp[5][0]);
    }
    return 0;
}

正解二：

http://blog.csdn.net/qq_32680617/article/details/51057963

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<cmath>
#define INF 0x3f3f3f3f
using namespace std;
const int maxn=1e5+5;
int a[11][maxn];
int main()
{
    int n,x,y;
    while(scanf("%d",&n)==1&&n)
    {
        memset(a,0,sizeof(a));
        int maxtime=-INF;
        for(int i=0;i<n;i++)
        {
            scanf("%d%d",&x,&y);
            maxtime=max(maxtime,y);
            a[x][y]++;
        }
        for(int i=maxtime-1;i>=0;i--)
        {
            for(int k=0;k<=10;k++)
            {
                if(k==0)
                {
                    a[k][i]+=max(a[k][i+1],a[k+1][i+1]);
                }
                else
                {
                    a[k][i]+=max(max(a[k][i+1],a[k-1][i+1]),a[k+1][i+1]);
                }
            }
        }
        printf("%d
",a[5][0]);
    }
    return 0;    
}

RE：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<cmath>
#define INF 0x3f3f3f3f
using namespace std;
const int maxn=1e5+5;
int a[11][maxn];
int main()
{
    int n,x,y;
    while(scanf("%d",&n)==1&&n)
    {
        memset(a,0,sizeof(a));
        int maxtime=-INF;
        for(int i=0;i<n;i++)
        {
            scanf("%d%d",&x,&y);
            maxtime=max(maxtime,y);
            a[x][y]++;
        }
        for(int i=maxtime-1;i>=0;i--)
        {
            for(int k=0;k<=10;k++)
            {
                if(k==0)
                {
                    a[k][i]+=max(a[k][i+1],a[k+1][i+1]);
                }
                else
                {
                    a[k][i]+=max(max(a[k][i+1],a[k-1][i+1]),a[k+1][i+1]);
                }
            }
        }
        printf("%d
",a[5][0]);
    }
    return 0;    
}

这份代码是按逆推写的，然而不知道为什么RE，看数组也没越界.....先放在这里.....