UVa357 Let Me Count The Ways DP多阶段决策问题

http://janfan.cn/chinese/2015/01/21/dynamic-programming.html

#include <cstdio>
#include <iostream>
#include <cstring>
#include <string>
#include <algorithm>
#include <map>

using namespace std;

const int N = 30000 + 5, NCOINS = 5;
long long arr[N];
int coins[] = { 1, 5, 10, 25, 50 };

#if 0
long long count_ways(int n) {
	int i1, i5, i10, i25, i50;
	long long cnt = 0;
	for (i1 = 0; i1 <= n; i1++) {
		for (i5 = 0; i5 * 5 <= n; i5++) {
			for (i10 = 0; i10 * 10 <= n; i10++) {
				for (i25 = 0; i25 * 25 <= n; i25++) {
					for (i50 = 0; i50 * 50 <= n; i50++) {
						int tmp = i1 + i5 * 5 + i10 * 10 + i25 * 25 + i50 * 50;
						if (tmp == n) cnt++;
					}
				}
			}
		}
	}
	return cnt;
}
#endif

#if 1
long long count_ways_dp(int n) {
	memset(arr, 0, sizeof(arr));
	arr[0] = 1;
	for (int i = 0; i < NCOINS; i++) {
		for (int j = coins[i]; j <= n; j++) {
			arr[j] += arr[j - coins[i]];
		}
	}
	return arr[n];
}
#endif

int main()
{
	int n;
	while (~scanf("%d", &n)) {
		long long ans = count_ways_dp(n);
		if (ans > 1) {
			printf("There are %lld ways to produce %d cents change.\n", ans, n);
		}
		else {
			printf("There is only %lld way to produce %d cents change.\n", ans, n);
		}
	}
	return 0;
}