「百度之星2017」程序设计大赛 初赛(B)
好气啊突然发现复赛的时候要军训
1001.Chess
f(i,j)表示最后一个棋放在(i,j)的方案
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#include<map> #include<cmath> #include<ctime> #include<queue> #include<stack> #include<cstdio> #include<vector> #include<bitset> #include<cstring> #include<iostream> #include<algorithm> #define mod 1000000007 #define ll long long using namespace std; ll read() { ll x=0,f=1;char ch=getchar(); while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} return x*f; } int T; int n, m; int f[1005][1005], g[1005][1005]; int main() { T = read(); while(T--) { memset(f, 0, sizeof(f)); memset(g, 0, sizeof(g)); n = read(); m = read(); if(n > m)swap(n, m); for(int i = 1; i <= m; i++) { f[1][i] = 1; g[1][i] = i; } for(int i = 2; i <= n; i++) for(int j = 1; j <= m; j++) { f[i][j] = g[i - 1][j - 1]; g[i][j] = (g[i][j - 1] + f[i][j]) % mod; } cout << g[n][m] << endl; } return 0; } |
1002.Factory
把集合分为元素个数大于\(m = \sqrt{n}\)，和小等于 m 的
对于元素个数很多的集合，每个集合 bfs 一次，预处理出到其它集合的距离
如果询问的两个集合的元素个数都比较少，建一下虚树 dp
。。。我不慎误算复杂度把这里写成了记忆化搜索+暴力，结果还过了
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#include<map> #include<cmath> #include<ctime> #include<queue> #include<stack> #include<cstdio> #include<vector> #include<bitset> #include<cstring> #include<iostream> #include<algorithm> #define mod 1000000007 #define inf 1000000000 #define ll long long using namespace std; ll read() { ll x=0,f=1;char ch=getchar(); while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} return x*f; } bool vis[100005]; int T; int n, m, Q, id, cnt; int last[100005]; int mp[100005], q[100005], dis[100005]; int dep[100005], D[100005]; vector<int>G[100005], B[100005]; int ans[205][100005]; int fa[100005][17]; map<int, int>ANS[100005]; struct data{ int to, next, v; }e[200005]; int lca(int x, int y) { if(dep[x] < dep[y])swap(x, y); int d = dep[x] - dep[y]; for(int i = 0; i <= 16; i++) if((1 << i) & d)x = fa[x][i]; for(int i = 16; i >= 0; i--) if(fa[x][i] != fa[y][i]) x = fa[x][i], y = fa[y][i]; if(x == y)return x; return fa[x][0]; } void insert(int u, int v, int w) { e[++cnt].to = v; e[cnt].next = last[u]; e[cnt].v = w; last[u] = cnt; e[++cnt].to = u; e[cnt].next = last[v]; e[cnt].v = w; last[v] = cnt; } void bfs(int x) { memset(vis, 0, sizeof(vis)); memset(dis, 0, sizeof(dis)); if(!mp[x])mp[x] = ++id; int now = mp[x], l = 0, r = 0; for(int i = 0; i < G[x].size(); i++) { q[r] = G[x][i]; vis[G[x][i]] = 1; r++; } while(l <= r) { int u = q[l]; l++; for(int i = 0; i < B[u].size(); i++) ans[now][B[u][i]] = min(ans[now][B[u][i]], dis[u]); for(int i = last[u]; i; i = e[i].next) if(!vis[e[i].to]) { vis[e[i].to] = 1; dis[e[i].to] = dis[u] + e[i].v; q[r] = e[i].to; r++; } } } void dfs(int x) { for(int i = 1; i <= 16; i++) fa[x][i] = fa[fa[x][i - 1]][i - 1]; for(int i = last[x]; i; i = e[i].next) if(e[i].to != fa[x][0]) { fa[e[i].to][0] = x; D[e[i].to] = D[x] + e[i].v; dep[e[i].to] = dep[x] + 1; dfs(e[i].to); } } int getdis(int x, int y) { int f = lca(x, y); return D[x] + D[y] - 2 * D[f]; } int main() { T = read(); while(T--) { cnt = id = 0; memset(last, 0, sizeof(last)); memset(mp, 0, sizeof(mp)); memset(ans, 127, sizeof(ans)); for(int i = 1; i <= 100000; i++) { G[i].clear(); B[i].clear(); ANS[i].clear(); } n = read(); m = read(); for(int i = 1; i < n; i++) { int u = read(), v = read(), w = read(); insert(u, v, w); } for(int i = 1; i <= m; i++) { int x, y; x = read(); for(int j = 1; j <= x; j++) { y = read(); G[i].push_back(y); B[y].push_back(i); } } for(int i = 1; i <= m; i++) if(G[i].size() >= 500) bfs(i); dfs(1); Q = read(); for(int i = 1; i <= Q; i++) { int x = read(), y = read(); if(G[y].size() > G[x].size())swap(x, y); if(G[x].size() >= 500) { int now = mp[x]; printf("%d\n", ans[now][y]); } else { if(ANS[x][y]) printf("%d\n", ANS[x][y] - 1); else { int ans = inf; for(int p = 0; p < G[x].size(); p++) for(int q = 0; q < G[y].size(); q++) ans = min(ans, getdis(G[x][p], G[y][q])); ANS[x][y] = ans + 1; printf("%d\n", ans); } } } } return 0; } |
1005.度度熊的交易计划
预处理最短路，枚举n^2点对建图费用流
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#include<map> #include<cmath> #include<ctime> #include<queue> #include<stack> #include<cstdio> #include<vector> #include<bitset> #include<cstring> #include<iostream> #include<algorithm> #define inf 1000000000 #define mod 1000000007 #define ll long long using namespace std; ll read() { ll x=0,f=1;char ch=getchar(); while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} return x*f; } int T; int n, m, cnt, ans; int last[1005], q[1005], dis[1005]; int a[505], b[505], c[505], d[505]; int D[505][505]; struct edge{ int to,next,v,c; }e[200005]; bool mark[1005],inq[1005]; void insert(int u,int v,int w,int c) { e[++cnt]=(edge){v,last[u],w,c};last[u]=cnt; e[++cnt]=(edge){u,last[v],0,-c};last[v]=cnt; } bool spfa() { for(int i=0;i<=T;i++)dis[i]=-inf; int head=0,tail=1; q[0]=T;dis[T]=0; while(head!=tail) { int now=q[head];head++;if(head==1005)head=0; inq[now]=0; for(int i=last[now];i;i=e[i].next) if(e[i^1].v&&dis[now]-e[i].c>dis[e[i].to]) { dis[e[i].to]=dis[now]-e[i].c; if(!inq[e[i].to]) { q[tail++]=e[i].to; if(tail==1005)tail=0; inq[e[i].to]=1; } } } return dis[0]>0; } int dfs(int x,int f) { mark[x]=1; if(x==T)return f; int w,used=0; for(int i=last[x];i;i=e[i].next) if(e[i].v&&dis[x]-e[i].c==dis[e[i].to]&&!mark[e[i].to]) { w=dfs(e[i].to,min(e[i].v,f-used)); e[i].v-=w;e[i^1].v+=w; ans+=e[i].c*w;used+=w;if(used==f)return f; } return used; } void zkw() { while(spfa()) { for(int i=0;i<=T;i++)mark[i]=0; mark[T]=1; while(mark[T]) mark[T]=0,dfs(0,inf); } } int main() { while(scanf("%d%d", &n, &m) != EOF) { T = 2 * n + 1; cnt = 1; memset(last, 0, sizeof(last)); for(int i = 1; i <= n; i++) a[i] = read(), b[i] = read(), c[i] = read(), d[i] = read(); memset(D, 127 / 2, sizeof(D)); for(int i = 1; i <= n; i++) D[i][i] = 0; for(int i = 1; i <= m; i++) { int u = read(), v = read(), w = read(); D[u][v] = D[v][u] = min(D[u][v], w); } for(int k = 1; k <= n; k++) for(int i = 1; i <= n; i++) for(int j = 1; j <= n; j++) D[i][j] = min(D[i][j], D[i][k] + D[k][j]); for(int i = 1; i <= n; i++) for(int j = 1; j <= n; j++) if(D[i][j] + a[i] < c[j]) { insert(i, j + n, inf, c[j] - D[i][j] - a[i]); } for(int i = 1; i <= n; i++) { insert(0, i, b[i], 0); insert(i + n, T, d[i], 0); } ans = 0; zkw(); cout << ans << endl; } return 0; } |
1006.小小粉丝度度熊
先处理出互不相交的区间
枚举答案的左边第一个区间，最后一个区间是单调往右的
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#include<map> #include<cmath> #include<ctime> #include<queue> #include<stack> #include<cstdio> #include<vector> #include<bitset> #include<cstring> #include<iostream> #include<algorithm> #define mod 1000000007 #define ll long long using namespace std; ll read() { ll x=0,f=1;char ch=getchar(); while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} return x*f; } int n, m, top; int l[100005], r[100005], sum[100005]; struct data{ int l, r, sum; }a[100005], b[100005]; bool cmp(data a, data b) { return a.l < b.l; } int main() { while(scanf("%d%d", &n, &m) != EOF) { top = 0; for(int i = 1; i <= n; i++) a[i].l = read(), a[i].r = read(); sort(a + 1, a + n + 1, cmp); int l = 0, r = 0; for(int i = 1; i <= n; i++) { if(a[i].l <= r)r = max(r, a[i].r + 1); else { if(r)b[++top] = (data){l, r - 1, r - l}; l = a[i].l, r = a[i].r + 1; } } b[++top] = (data){l, r - 1, r - l}; for(int i = 1; i <= top; i++) sum[i] = sum[i - 1] + b[i].sum; r = 1; int ans = 0; for(int i = 1; i <= top; i++) { while(sum[r + 1] - sum[i - 1] + m >= b[r + 1].r - b[i].l + 1 && r + 1 <= top) r++; int t = (b[r].r - b[i].l + 1) - (sum[r] - sum[i - 1]); ans = max(ans, (b[r].r - b[i].l + 1) + m - t); } cout << ans << endl; } return 0; } |
计数器 9813855
OI 课件=>
OI 课件=>
上课偶遇大神，小人我口出狂言，谢罪，谢罪。
搞不懂你们学校这时候军训。
所以复赛就没有参加嘛