全T求调

SwethessPotion @ 2024-02-10 12:07:24

#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <cstdlib>
#include <ctime>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#define INT_MAX 2147483647
#define INT_MIN -2147483648
#define LLONG_MAX 9223372036854775807
#define LLONG_MIN -9223372036854775808
#define ll long long
using namespace std;

ll funcw[21][21][21];

ll w(ll a, ll b, ll c)
{
    if (a <= 0 || b <= 0 || c <= 0)
    {
        return 1;
    }
    if (a > 20 || b > 20 || c > 20)
    {
        a = 20, b = 20, c = 20;
    }
    if (funcw[a][b][c] != 0) return funcw[a][b][c];
    if (a < b && b < c)
    {
        return w(a, b, c - 1) + w(a - 1, b - 1, c) + w(a - 1, b, c - 1) - w(a - 1, b - 1, c - 1);
    }
    return w(a - 1, b, c) + w(a - 1, b - 1, c) + w(a - 1, b, c - 1) - w(a - 1, b - 1, c - 1);
}

int main()
{
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(false);
    ll a, b, c;
    cin >> a >> b >> c;
    while (a != -1 || b != -1 || c != -1)
    {
        cout << "w(" << a << ", " << b << ", " << c << ") = " << w(a, b, c) << endl;
        cin >> a >> b >> c;
    }
    return 0;
}

by him0715 @ 2024-02-11 11:36:49

//首先，你引入了一堆没有必要的头文件（看上去很麻烦
//然后，你的记忆化搜索只在第37行出现过一次，应该在四个if+最后的return里都使用，所以你这funcw[21][21][21]就等于没用一样
//改动后的函数部分：
ll w(ll a, ll b, ll c){
    if (a <= 0 || b <= 0 || c <= 0)
        return 1;
    if (a > 20 || b > 20 || c > 20)
        return w(20, 20, 20);
    if (funcw[a][b][c] != 0)
        return funcw[a][b][c];
    if (a < b && b < c)
        return funcw[a][b][c] = w(a, b, c - 1) + w(a, b - 1, c - 1) - w(a, b - 1, c);
    return funcw[a][b][c] = w(a - 1, b, c) + w(a - 1, b - 1, c) + w(a - 1, b, c - 1) - w(a - 1, b - 1, c - 1);
}

by him0715 @ 2024-02-11 11:37:11

这样就可以AC了

by qusia_MC @ 2024-02-12 19:20:18

这么多头文件（好像一个iostream就够了）我怀疑你在炫技但我没有证据

说正事，额你这个只开了个数组啊，相当于你用记忆化搜索，但是啥也没记，这不就相当于啥也没有？

应该把赋值的也整上，这样就相当于记住了，才能不重复计算：

改动：

这个部分：return w(a, b, c - 1) + w(a - 1, b - 1, c) + w(a - 1, b, c - 1) - w(a - 1, b - 1, c - 1);改为：return funcw[a][b][c]=w(a, b, c - 1) + w(a - 1, b - 1, c) + w(a - 1, b, c - 1) - w(a - 1, b - 1, c - 1);

还有，下面的return，也同上，在那一串东西的前面加个funcw[a][b][c]=

by qusia_MC @ 2024-02-12 19:20:37

@ SwethessPotion

by qusia_MC @ 2024-02-12 19:20:52

@SwethessPotion

by qusia_MC @ 2024-02-12 19:27:04

最后附上我的AC代码（你那个里头不必要的东西太多）

#include<bits/stdc++.h>
using namespace std;
#define int long long
int k,w[21][21][21];
int psort(int a,int b,int c)
{
    if(a<=0||b<=0||c<=0)return 1;
    //情况1
    if(a>20||b>20||c>20)
    {
        return psort(20,20,20);
    }//情况2
    if(w[a][b][c]!=0)return w[a][b][c];
    //脑子里记住了，下次不必要算一遍，拿记忆来就可以
    if(a<b&&b<c)return w[a][b][c]=psort(a,b,c-1)+psort(a,b-1,c-1)-psort(a,b-1,c);
    //情况3
    else return w[a][b][c]=psort(a-1,b,c)+psort(a-1,b-1,c)+psort(a-1,b,c-1)-psort(a-1,b-1,c-1);
    //最后一种
}
signed main()
{
    int a,b,c;
    psort(20,20,20);
    while(1)
    {
        cin>>a>>b>>c;
        if(a==-1&&b==-1&&c==-1)return 0;
        //结束标志
        printf("w(%lld, %lld, %lld) = %d\n",a,b,c,psort(a,b,c));
        //printf很方便
    }
    return 0;
}

总结：记忆化搜索不仅要调用记忆，还要往脑子里记东西

by SwethessPotion @ 2024-02-13 09:17:53

谢谢 @\text{William2019} @\text{him0175}