poj_3181

/*
 * 高精度完全背包
 * High precision completely backpack
*/
#include <cstdio>
#include <cstring>

#define MAXN	1001
#define MAXLEN	50

char dp[MAXN][MAXLEN], zero[MAXLEN];

void add(int u, int v)
{
	int tmp_val, bit(0);
	for(int i = MAXLEN-1; i >= 0; i --) {
		tmp_val = dp[v][i]-'0'+dp[u][i]-'0'+bit;
		dp[v][i] = tmp_val%10+'0';
		bit = tmp_val/10;
	}
}

void complete_knapsack(int n, int k)
{
	int pos(0);
	memset(dp, '0', sizeof(dp));
	dp[0][MAXLEN-1] = '1';
	for(int i = 1; i <= k; i ++) {
		for(int v = 0; v <= n-i; v ++) {
			if( 1 == strcmp(dp[v], zero) ) {
				add(v, v+i);
			}
		}
	}
	while( '0' == dp[n][pos] ) {
		pos ++;
	}
	while( pos < MAXLEN ) {
		printf("%c", dp[n][pos ++]);
	}
	printf("\n");
}

int main(int argc, char const *argv[])
{
#ifndef ONLINE_JUDGE
	freopen("test.in", "r", stdin);
#endif
	int n, k;
	memset(zero, '0', sizeof(zero));
	while( ~scanf("%d %d", &n, &k) ) {
		complete_knapsack(n, k);
	}
	return 0;
}