POJ 1579 Function Run Fun(记忆化)

Function Run Fun

#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;

int dp[25][25][25];

int dfs(int a,int b,int c)
{
    if(a <= 0 || b <= 0 || c <= 0)
        return 1;

    if(a > 20 || b > 20 || c > 20)
        return dfs(20, 20, 20);

    if(dp[a][b][c])
        return dp[a][b][c];

    if(a < b && b < c)
        dp[a][b][c] = dfs(a, b, c-1) + dfs(a, b-1, c-1) - dfs(a, b-1, c);
    else
        dp[a][b][c] = dfs(a-1, b, c) + dfs(a-1, b-1, c) + dfs(a-1, b, c-1) - dfs(a-1, b-1, c-1);

    return dp[a][b][c];
}

int main()
{
    int a,b,c;

    memset(dp,0,sizeof(dp));

    while(~scanf("%d%d%d", &a, &b, &c))
    {
        if(a == -1 && b == -1 && c == -1)
            break;

        printf("w(%d, %d, %d) = %d\n", a, b, c, dfs(a,b,c));
    }

    return 0;
}