Codeforces 313

A. Ilya and Bank Account 水题

B. Ilya and Queries 水，维护区间和

C. Ilya and Matrix

贪心。大的明显会被多次取。

/**

 * Problem:313C

 * Author:Shun Yao

 * Time:2013.5.31

 * Result:Accepted

 * Memo:greedy

 */



#include <cstdio>

#include <algorithm>

#include <functional>



const long MaxN = 2000001;



long n, N, a[MaxN];

long long s[MaxN], ans;



int main() {

	static long i;

	scanf("%ld", &N);

	for (i = 1; i <= N; ++i)

		scanf("%ld", a + i);

	std::sort(a + 1, a + N + 1, std::greater<long>());

	s[0] = 0;

	for (i = 1; i <= N; ++i)

		s[i] = s[i - 1] + a[i];

	ans = 0;

	for (i = 1; i <= N; i <<= 2)

		ans += s[i];

	printf("%lld", ans);

	return 0;

}

 D. Ilya and Roads

好吧，dp。。。

 状态很好想，f[i][j]代表前i个人覆盖了j个。

然后是g[i][j]代表覆盖区间 i -- j 的最小cost；

转移见code:

/**

 * Problem:313D

 * Author:Shun Yao

 * Time:2013.6.3

 * Result:Accepted

 * Memo:DP

 */



#include <cstdio>



long long min(long long x, long long y) {

	return x < y ? x : y;

}



const long Maxn = 305;

const long long inf = 1LL << 60;



long n, m, K;

long long g[Maxn][Maxn], f[Maxn][Maxn], ans;



int main() {

	static long a, b, c, i, j, k;

	scanf("%ld%ld%ld", &n, &m, &K);

	for (i = 0; i <= n; ++i)

		for (j = 0; j <= n; ++j)

			g[i][j] = inf;

	for (i = 1; i <= m; ++i) {

		scanf("%ld%ld%ld", &a, &b, &c);

		g[a][b] = min(g[a][b], c);

	}

	for (i = 1; i <= n; ++i)

		for (j = i; j <= n; ++j)

			g[i][j] = min(g[i][j], g[i - 1][j]);

	for (i = 0; i <= n; ++i) {

		f[i][0] = 0;

		for (j = 1; j <= n; ++j)

			f[i][j] = inf;

	}

	for (i = 1; i <= n; ++i)

		for (j = 0; j <= i; ++j) {

			f[i][j] = f[i - 1][j];

			for (k = i - j + 1; k <= i; ++k)

				if (f[k - 1][j - (i - k + 1)] != inf && g[k][i] != inf)

					f[i][j] = min(f[i][j], f[k - 1][j - (i - k + 1)] + g[k][i]);

		}

	ans = inf;

	for (i = K; i <= n; ++i)

		if (ans > f[n][i])

			ans = f[n][i];

	printf("%I64d", ans == inf ? -1 : ans);

	return 0;

}

E. Ilya and Two Numbers

贪心，构造。

/**

 * Problem:313E

 * Author:Shun Yao

 * Time:2013.6.15

 * Result:Acceped

 * Memo:constructive algorithms, greedy

 */



#include <cstring>

#include <cstdio>

#include <functional>

#include <algorithm>



#define Maxn 100005



long n, m, a[Maxn], b[Maxn], c[Maxn], d[Maxn], ans[Maxn];



int main() {

	static long i, x, l;

#ifndef ONLINE_JUDGE

	freopen("e.in", "r", stdin);

	freopen("e.out", "w", stdout);

#endif

	memset(a, 0, sizeof a);

	memset(b, 0, sizeof b);

	scanf("%ld%ld", &n, &m);

	for (i = 1; i <= n; ++i) {

		scanf("%ld", &x);

		++a[x];

	}

	for (i = 1; i <= n; ++i) {

		scanf("%ld", &x);

		++b[x];

	}

	ans[0] = 0;

	d[0] = 0;

	for (i = m - 1; i >= 0; --i) {

		while (b[m - 1 - i]--)

			c[++l] = m - 1 - i;

		while (a[i]--) {

			if (l)

				ans[++ans[0]] = i + c[l--];

			else

				d[++d[0]] = i;

		}

	}

	for (i = 1; i <= d[0]; ++i)

		ans[++ans[0]] = d[i] + c[l--] - m;

	std::sort(ans + 1, ans + n + 1, std::greater<long>());

	for (i = 1; i <= n; ++i)

		printf("%ld ", ans[i]);

	return 0;

}