B. Math Show 暴力 C - Four Segments

B. Math Show

这个题目直接暴力，还是有点难想，我没有想出来，有点思维。

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <vector>
#include <string>
#include <algorithm>
#include <iostream>
#include <map>
#include <list>
#define inf 0x3f3f3f3f
#define inf64 0x3f3f3f3f3f3f3f3f
using namespace std;
typedef long long ll;
const int maxn = 1e6 + 10;
int a[110], vis[110];
int sum[110];
int main()
{
	int n, k, m, ans = 0, sum = 0;
	scanf("%d%d%d", &n, &k, &m);
	for (int i = 1; i <= k; i++) {
		scanf("%d", &a[i]);
		sum += a[i];
	}
	sort(a + 1, a + 1 + k);
	for (int i = 0; i <= n; i++) {
		int res = m - i * sum;
		if (res < 0) break;
		int num = (k + 1)*i;
		for (int j = 1; j <= k; j++) {
			if (res >= a[j] * (n - i)) {
				res -= a[j] * (n - i);
				num += n - i;
			}
			else {
				num += res / a[j];
				break;
			}
		}
		ans = max(ans, num);
	}
	printf("%d\n", ans);
	return 0;
}

　　

C. Four Segments

这个题目我觉得还是有点难，这个题目求 res= sum[1,x-1] - sum[x,y-1] + sum[y,z-1] -sum[z, n] 的最大值

暴力枚举中间的y，然后两边贪心求x , z

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <vector>
#include <string>
#include <algorithm>
#include <iostream>
#include <map>
#include <list>
#define inf 0x3f3f3f3f
#define inf64 0x3f3f3f3f3f3f3f3f
using namespace std;
typedef long long ll;
const int maxn = 5e3 + 10;
ll sum[maxn], a[maxn];

int main()
{
	int n;
	scanf("%d", &n);
	for (int i = 1; i <= n; i++) scanf("%lld", &a[i]), sum[i] = sum[i - 1] + a[i];
	ll ans = 0, x = 1, y = 1, z = 1;
	for(int i=1;i<=n;i++)
	{
		ll res1 = 0, mark1 = 1;
		for (int j = i; j <= n + 1; j++) {
			ll num = sum[j - 1] * 2 - sum[i - 1] - sum[n];
			if (num > res1)	res1 = num, mark1 = j;
		}
		ll res2 = 0, mark2 = 1;
		for (int j = 1; j <= i; j++) {
			ll num = 2 * sum[j - 1] - sum[i - 1];
			if (num > res2) res2 = num, mark2 = j;
		}
		if(res1+res2>ans)
		{
			ans = res1 + res2;
			x = mark2, y = i, z = mark1;
			// printf("ans=%d\n", ans);
		}
	}
	printf("%lld %lld %lld\n", x - 1, y - 1, z - 1);
	return 0;
}