The 2014 ACM-ICPC Asia Mudanjiang Regional Contest(2014牡丹江区域赛）

The 2014 ACM-ICPC Asia Mudanjiang Regional Contest

题目链接

没去现场，做的网络同步赛，感觉还可以，搞了6题

A：这是签到题，对于A堆除掉，如果没剩余在减一，B堆直接除掉 + 1就可以了

B：二分贪心，二分长度，然后会发现本质上是在树上最长链上找两点，那么有二分出来的长度了，就从两端分别往里移动那么长，那两个位置就是放置位置，然后在判断一下就可以了

D：概率DP，首先知道放一个棋子，可以等价移动到右上角区域，那么就可以dp[x][y][k]，表示已经完成x行y列，已经放了k个棋子，那么棋盘被划分成4个区域，利用这个区域可以算概率，然后去转移即可

H：字符串处理，先hash掉，记录每个hash值对应的l，r区间，离线处理完每次询问输出就可以了，注意细节

I：签到题，注意0的时候是等于0就可以了

K：贪心，如果数字个数不够，在前面补是最优的，然后从左往右扫描一遍，每次遇到1个星号要扣掉两个数字，如果没有，这需要交换操作，交换肯定和最后面的数字交换是最优的，最后还要考虑一种特殊情况，就是没有交换，并且最后还有数字，这时候要添加一个星号

代码：

A：

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 55;int t, n, m;int a, b, suma, sumb;int main() {scanf("%d", &t);while (t--) {scanf("%d%d", &n, &m);suma = sumb = 0;for (int i = 0; i < n - 1; i++) {scanf("%d", &a);suma += a;}for (int i = 0; i < m; i++) {scanf("%d", &b);sumb += b;}int l, r;l = suma / (n - 1) - (suma % (n - 1) == 0);r = sumb / m + 1;if (l > r) swap(l, r);printf("%d %d\n", l, r);}return 0;}

B：

#include <cstdio>#include <cstring>#include <queue>#include <algorithm>using namespace std;const int N = 200005;struct Edge {int u, v;Edge() {}Edge(int u, int v) {this->u = u;this->v = v;}} E[N * 2];int first[N], next[N * 2], en;void add_Edge(int u, int v) {E[en] = Edge(u, v);next[en] = first[u];first[u] = en++;}const int INF = 0x3f3f3f3f;int t, n, vis[N], f[N], u1, u2, Q[N * 2];int bfs(int root) {int head = 0, rear = 0;vis[root] = 0;Q[rear++] = root;f[root] = 0;int u;while (head < rear) {u = Q[head++];for (int i = first[u]; i + 1; i = next[i]) {Edge e = E[i];int v = e.v;if (vis[v] > vis[u] + 1) {vis[v] = vis[u] + 1;f[v] = u;Q[rear++] = v;}}}return u;}bool judge(int len) {memset(vis, INF, sizeof(vis));u1 = bfs(1);for (int i = 0; i < len; i++) {if (f[u1] == 0) {u2 = u1 % n + 1;return true;}u1 = f[u1];}memset(vis, INF, sizeof(vis));u2 = bfs(u1);for (int i = 0; i < len; i++) {if (f[u2] == 0) return true;u2 = f[u2];}bfs(u2);for (int i = 1; i <= n; i++)if (vis[i] > len) return false;return true;}int main() {scanf("%d", &t);while (t--) {en = 0;memset(first, -1, sizeof(first));scanf("%d", &n);int u, v;for (int i = 1; i < n; i++) {scanf("%d%d", &u, &v);add_Edge(u, v);add_Edge(v, u);}if (n == 2) {printf("0 1 2\n");continue;}int l = 0, r = n;while (l < r) {int mid = (l + r) / 2;if (judge(mid)) r = mid;else l = mid + 1;}judge(l);if (u1 == u2) u2 = u2 % n + 1;printf("%d %d %d\n", l, u1, u2);}return 0;}

D：

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 55;int t, n, m;double dp[N][N][N * N];int main() {scanf("%d", &t);while (t--) {scanf("%d%d", &n, &m);memset(dp, 0, sizeof(dp));dp[0][0][0] = 1;for (int i = 1; i <= n; i++) {for (int j = 1; j <= m; j++) {for (int k = max(i, j); k <= i * j; k++) {double p1 = (i * j - (k - 1)) * 1.0;double p2 = (n - i + 1) * j;double p3 = i * (m - j + 1);double p4 = (n - i + 1) * (m - j + 1);dp[i][j][k] = dp[i][j][k - 1] * p1 + dp[i - 1][j][k - 1] * p2 + dp[i][j - 1][k - 1] * p3 + dp[i - 1][j - 1][k - 1] * p4;dp[i][j][k] /= (n * m - (k - 1));}}}double ans = 0;for (int i = max(n, m); i <= n * m; i++)ans += dp[n][m][i] * i - dp[n][m][i - 1] * i;printf("%.12lf\n", ans);}return 0;}

H：

#include <cstdio>#include <cstring>#include <map>using namespace std;#define MP(a,b) make_pair(a,b)typedef unsigned long long ull;const ull x = 123;const int N = 200005;typedef pair<int, int> pii;char str[N], q[N];map<ull, pii> g;int t, u, k, lens;int build(ull st) {int flag = 1;while (u < lens) {if (str[u] == '{') {flag = 0;u++;}if (str[u] == '}') {u++;return u;}ull nt = st;while (str[u] != ':' && str[u] != ',' && str[u] != '}')nt = nt * x + str[u++];if (str[u] == ':') {int l = ++u;int r = build(nt * x + '.');g[nt] = MP(l, r);}if (str[u] == '}') {if (!flag)u++;return u;}if (str[u] == ',') {if (flag) return u;u++;}}}int main() {scanf("%d", &t);while (t--) {u = 0;g.clear();scanf("%s", str);lens = strlen(str);build(0);scanf("%d", &k);while (k--) {scanf("%s", q);ull tmp = 0;int len = strlen(q);for (int i = 0; i < len; i++)tmp = tmp * x + q[i];if (!g.count(tmp)) {printf("Error!\n");continue;}int l = g[tmp].first, r = g[tmp].second;for (int i = l; i < r; i++)printf("%c", str[i]);printf("\n");}}return 0;}

I：

#include <cstdio>#include <cstring>#include <cmath>int t, n;char str[10];double solve(int x) {if (x == 0) return 0;double sb = x * 1.0 / 100;if (str[0] == 'b') return sb * log2(sb);if (str[0] == 'n') return sb * log(sb);if (str[0] == 'd') return sb * log10(sb);}int main() {scanf("%d", &t);while (t--) {scanf("%d%s", &n, str);double ans = 0;int x;for (int i = 0; i < n; i++) {scanf("%d", &x);ans += solve(x);}printf("%.12lf\n", -ans);}return 0;}

K：

#include <cstdio>#include <cstring>#include <map>using namespace std;#define MP(a,b) make_pair(a,b)typedef unsigned long long ull;const ull x = 123;const int N = 200005;typedef pair<int, int> pii;char str[N], q[N];map<ull, pii> g;int t, u, k, lens;int build(ull st) {int flag = 1;while (u < lens) {if (str[u] == '{') {flag = 0;u++;}if (str[u] == '}') {u++;return u;}ull nt = st;while (str[u] != ':' && str[u] != ',' && str[u] != '}')nt = nt * x + str[u++];if (str[u] == ':') {int l = ++u;int r = build(nt * x + '.');g[nt] = MP(l, r);}if (str[u] == '}') {if (!flag)u++;return u;}if (str[u] == ',') {if (flag) return u;u++;}}}int main() {scanf("%d", &t);while (t--) {u = 0;g.clear();scanf("%s", str);lens = strlen(str);build(0);scanf("%d", &k);while (k--) {scanf("%s", q);ull tmp = 0;int len = strlen(q);for (int i = 0; i < len; i++)tmp = tmp * x + q[i];if (!g.count(tmp)) {printf("Error!\n");continue;}int l = g[tmp].first, r = g[tmp].second;for (int i = l; i < r; i++)printf("%c", str[i]);printf("\n");}}return 0;}