我觉得我代码没有问题，但全WA

#include<bits/stdc++.h>
using namespace std; 
#define ll long long
ll x[25][25][25];
ll a , b , c;
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 (a < b && b < c) 
    {
        if (x[a][b][c-1] == 0) x[a][b][c-1] = w(a , b , c - 1);
        if (x[a][b-1][c-1] == 0) x[a][b-1][c-1] = w(a , b - 1 , c - 1);
        if (x[a][b-1][c] == 0) x[a][b-1][c] = w(a , b - 1 , c);
        x[a][b][c] = x[a][b][c-1] + x[a][b-1][c-1] + x[a][b-1][c];
    }
    else
    {
        if (x[a-1][b][c] == 0) x[a-1][b][c] = w(a - 1 , b , c);
        if (x[a-1][b-1][c] == 0) x[a-1][b-1][c] = w(a - 1 , b - 1 , c);
        if (x[a-1][b][c-1] == 0) x[a-1][b][c-1] = w(a - 1 , b , c - 1);
        if (x[a-1][b-1][c-1] == 0) x[a-1][b-1][c-1] = w(a - 1 , b - 1 , c - 1);
        x[a][b][c] = x[a-1][b][c] + x[a-1][b-1][c] + x[a-1][b][c-1] - x[a-1][b-1][c-1];
    }
    return x[a][b][c];
}
int main ()
{
    while (scanf ("%lld%lld%lld" , &a , &b , &c))
    {
        if ((a == -1) && (b == -1) && (c == -1)) return 0;
        printf("w(%lld, %lld, %lld) = ", a, b, c);
        printf("%lld\n", w(a, b, c));
    }
}

帮我看一看代码错在哪里