CSU-ACM2014年校队选拔赛指导赛解题报告
•Problem A CSU 1065 贪心
1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 using namespace std; 5 const int maxn = 1000010; 6 struct Node{ 7 int a,b; 8 bool operator < (const Node& rhs) const{ 9 return b < rhs.b; 10 } 11 }node[maxn]; 12 13 int main(){ 14 int n,r = -1,ans = 0; 15 scanf("%d",&n); 16 for(int i = 0;i < n;i++){ 17 scanf("%d%d",&node[i].a,&node[i].b); 18 } 19 sort(node,node+n); 20 for(int i = 0;i < n;i++){ 21 if(node[i].a > r){ 22 ans++; 23 r = node[i].b; 24 } 25 } 26 printf("%d\n",ans); 27 return 0; 28 }
•Problem B CSU 1060 DP
1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 using namespace std; 5 const int maxn = 110; 6 char s1[maxn],s2[maxn],s3[maxn]; 7 int dp[maxn][maxn][maxn]; 8 9 int main(){ 10 while(scanf("%s",s1+1) != EOF){ 11 scanf("%s",s2+1); 12 scanf("%s",s3+1); 13 int len1 = strlen(s1+1); 14 int len2 = strlen(s2+1); 15 int len3 = strlen(s3+1); 16 memset(dp,0,sizeof(dp)); 17 18 for(int i = 1;i <= len1;i++){ 19 for(int j = 1;j <= len2;j++){ 20 for(int k = 1;k <= len3;k++){ 21 if(s1[i] == s2[j] && s2[j] == s3[k]){ 22 dp[i][j][k] = dp[i-1][j-1][k-1]+1; 23 }else{ 24 int tmp1 = dp[i-1][j][k]; 25 int tmp2 = dp[i][j-1][k]; 26 int tmp3 = dp[i][j][k-1]; 27 tmp1 = max(tmp1,tmp2); 28 tmp1 = max(tmp1,tmp3); 29 dp[i][j][k] = tmp1; 30 } 31 } 32 } 33 } 34 35 printf("%d\n",dp[len1][len2][len3]); 36 } 37 return 0; 38 }
•Problem C CSU 1307 最短路
1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 #include <queue> 5 using namespace std; 6 typedef pair<int,int> pii; 7 const int maxn = 2010; 8 const int maxm = 100010; 9 int v[maxm],next[maxm],w[maxm]; 10 int d[maxm],first[maxn],e; 11 void init(){ 12 e = 0; 13 memset(first,-1,sizeof(first)); 14 } 15 16 void add_edge(int a,int b,int c){ 17 v[e] = b;next[e] = first[a];w[e] = c;first[a] = e++; 18 } 19 20 int dijkstra(int src,int dist,int mid){ 21 priority_queue <pii,vector<pii>,greater<pii> > q; 22 memset(d,-1,sizeof(d)); 23 d[src] = 0; 24 q.push(make_pair(0,src)); 25 while(!q.empty()){ 26 while(!q.empty() && q.top().first > d[q.top().second]) q.pop(); 27 if(q.empty()) break; 28 int u = q.top().second; 29 q.pop(); 30 for(int i = first[u];i != -1;i = next[i])if(w[i] <= mid){ 31 if(d[v[i]] > d[u] + w[i] || d[v[i]] == -1){ 32 d[v[i]] = d[u]+w[i]; 33 q.push(make_pair(d[v[i]],v[i])); 34 } 35 } 36 } 37 return d[dist]; 38 } 39 40 int main(){ 41 int n,m,src,dist; 42 while(scanf("%d%d%d%d",&n,&m,&src,&dist) != EOF){ 43 init(); 44 int l = 1<<30,r = -1,ans = 1<<30; 45 for(int i = 0;i < m;i++){ 46 int a,b,c; 47 scanf("%d%d%d",&a,&b,&c); 48 add_edge(a,b,c); 49 add_edge(b,a,c); 50 l = min(l,c); 51 r = max(r,c); 52 } 53 while(l <= r){ 54 int mid = (l+r)>>1; 55 int tmp = dijkstra(src,dist,mid); 56 if(tmp == -1) l = mid+1; 57 else r = mid-1,ans = tmp; 58 } 59 60 printf("%d\n",ans); 61 } 62 return 0; 63 }
•Problem D CSU 1290 DP
1 #include <cstdio> 2 double dp[1005]; 3 int main() 4 { 5 int n,t; 6 double k; 7 scanf("%d", &t); 8 while (t--) { 9 scanf("%lf %d", &k, &n); 10 dp[1] = 1.0; 11 for (int i = 2; i <= n; ++i) 12 dp[i] = dp[i-1] + (k - dp[i-1])/k; 13 printf("%.5f\n", dp[n]); 14 } 15 return 0; 16 }
