【HDUOJ】几道递推DP

就不写题解了。很基础的递推。

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HDU2084数塔

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2084

代码：

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>

using namespace std;
const int maxn = 105;

int dp[maxn][maxn];
int a[maxn][maxn];

int main(){
    int T;
    cin>>T;
    while(T--){
        memset(a,0,sizeof(a));
        memset(dp,0,sizeof(dp));
        int n;
        cin>>n;
        for(int i = 1; i <= n ;i++){
            for(int j = 1; j <= i; j++){
                cin>>a[i][j];
            }
        }

        for(int i = n; i > 0; i--){
            for(int j = 1; j <= n ;j++){
                dp[i][j] = max(dp[i+1][j] ,dp[i+1][j+1]) + a[i][j];
            }
        }
        cout<<dp[1][1]<<endl;
    }


    return 0;
}

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HDU2018母牛的故事

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2018

代码：

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>

using namespace std;
const int maxn = 105;
int dp[maxn];

void init(){
    dp[1] = 1;
    dp[2] = 2;
    dp[3] = 3;
    dp[4] = 4;
    dp[5] = 6;
    for(int i = 6; i <= 55; i++){
        dp[i] = dp[i-1] + dp[i-3];
    }
}

int main(){
    int n;
    init();
    while(cin>>n && n){
        cout<<dp[n]<<endl;
    }

    return 0;
}

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HDU2044小蜜蜂的故事

同类型HDU2041

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2044

代码：

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#define ll long long
using namespace std;
const int maxn = 55;
ll fib[maxn];

void init(){
    fib[0] = 0;
    fib[1] = 1;
    fib[2] = 2;
    for(int i = 3 ;i <= maxn ;i++){
        fib[i] = fib[i-1] + fib[i-2];
    }
}

int main(){
    init();
    int n,m;
    int T;
    cin>>T;
    while(T--){
        cin>>n>>m;
        cout<<fib[m-n]<<endl;
    }


    return 0;
}

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HDU2050

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2050

代码：

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#define ll long long
using namespace std;
const int maxn = 10005;
ll dp[maxn];

void init(){
    dp[1] = 2;
    dp[2] = 7;
    for(int i = 3; i <= maxn; i++){
        dp[i] = dp[i-1] + 4*(i-1) + 1;
    }
}

int main(){
    int T;
    cin>>T;
    int n;
    init();
    while(T--){
        cin>>n;
        cout<<dp[n]<<endl;
    }

    return 0;
}