poj1579

记忆化搜索

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

#define maxn 25

int a, b, c;
int f[maxn][maxn][maxn];

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

int main()
{
    memset(f, -1, sizeof(f));
    //freopen("t.txt", "r", stdin);
    while (scanf("%d%d%d", &a, &b, &c), ~a | ~b | ~c)
        printf("w(%d, %d, %d) = %d\n", a, b, c,  w(a, b, c));    
    return 0;
}