Ural 1114. Boxes (DP)

Http://acm.timus.ru/problem.aspx? Space = 1 & num = 1114

There are n boxes and balls of two colors. The red balls and the basketball balls are A and B respectively. Now, you can freely put the ball into the box. Each box can be in one color, two colors. How many methods are available.

Set DP [I] [J] [k] to indicate that J red balls and K basketball balls are left in the I-th box. The state transition equation can be listed: DP [I] [J] [k] = Σ (DP [I-1] [JJ] [Kk]) (j <= JJ <= A and K <= KK <= B ).

#include <stdio.h>#include <iostream>#include <map>#include <set>#include <bitset>#include <list>#include <stack>#include <vector>#include <math.h>#include <string.h>#include <queue>#include <string>#include <stdlib.h>#include <algorithm>#define LL __int64//#define LL long long#define ULL unsigned long long#define eps 1e-9#define PI acos(-1.0)using namespace std;ULL dp[25][20][20];int main(){    int n,A,B;    while(~scanf("%d %d %d",&n,&A,&B))    {        memset(dp,0,sizeof(dp));        dp[0][A][B] = 1;        ULL ans = 0;        for(int i = 1; i <= n; i++)        {            for(int j = 0; j <= A; j++)            {                for(int k = 0; k <= B; k++)                {                   for(int jj = j; jj <= A; jj++)                   {                       for(int kk = k; kk <= B; kk++)                            dp[i][j][k] += dp[i-1][jj][kk];                   }                   if(i == n )                        ans += dp[i][j][k];                }            }        }        printf("%I64u\n",ans);    }    return 0;}

Ural 1114. Boxes (DP)