还是只会4道。。sad。。。
A：SwapSort
用一个数组存储排好序之后。然后从头开始依次将需要交换的与本来应该在这个位置的交换，最多交换n-1次。
代码如下；
#include <iostream>#include <cstdio>#include <string>#include <cstring>#include <stdlib.h>#include <math.h>#include <ctype.h>#include <queue>#include <map>#include <set>#include <algorithm>using namespace std;int a[4000], b[4000], c[4000], d[4000];int main(){ int i, j, n, pos, cnt; while(scanf("%d",&n)!=EOF) { cnt=0; for(i=0;i<n scanf b sort for if pos="j;" break swap c printf return> <br> B： BerSU Ball <p></p> <p>二分图最大匹配裸题。</p> <p>代码如下：</p> <p></p> <pre name="code" class="sycode">#include <iostream>#include <cstdio>#include <string>#include <cstring>#include <stdlib.h>#include <math.h>#include <ctype.h>#include <queue>#include <map>#include <set>#include <algorithm>using namespace std;int link[200], vis[200], n, m, a[200], b[200];int head[200], cnt;struct node{ int u, v, next;}edge[100000];void add(int u, int v){ edge[cnt].v=v; edge[cnt].next=head[u]; head[u]=cnt++;}int dfs(int u){ int i; for(i=head[u];i!=-1;i=edge[i].next) { int v=edge[i].v; if(!vis[v]) { vis[v]=1; if(link[v]==-1||dfs(link[v])) { link[v]=u; return 1; } } } return 0;}void hungary(){ int i, ans=0; memset(link,-1,sizeof(link)); for(i=0;i<n memset if ans printf main int i j while for scanf cnt="0;" add hungary return> <br> C： Given Length and Sum of Digits... <p></p> <p>贪心水题。</p> <p>按照顺序依次填充。</p> <p>代码如下：</p> <p></p> <pre name="code" class="sycode">#include <iostream>#include <cstdio>#include <string>#include <cstring>#include <stdlib.h>#include <math.h>#include <ctype.h>#include <queue>#include <map>#include <set>#include <algorithm>using namespace std;#define LL __int64const int INF=0x3f3f3f3f;int a[1000], b[1000];int main(){ int m, s, i, j, x; while(scanf("%d%d",&m,&s)!=EOF) { if(m*9<s printf continue if else x="s-1;" for i>=2; i--) { if(x>=9) { a[i]=9; x-=9; } else if(x>=0&&x=9) { b[i]=9; x-=9; } else if(x>=0&&x <br> D： Unbearable Controversy of Being </s><p></p> <p>枚举起点，分别进行BFS找到距离为2的点，然后记录到达这个点的次数，若次数大于2，说明存在，根据组合数来求解。</p> <p>代码如下：</p> <p></p> <pre name="code" class="sycode">#include <iostream>#include <cstdio>#include <string>#include <cstring>#include <stdlib.h>#include <math.h>#include <ctype.h>#include <queue>#include <map>#include <set>#include <algorithm>using namespace std;#define LL __int64LL vis[4000], ans;int head[4000], cnt, n;struct node{ int u, v, next;}edge[50000];void add(int u,int v){ edge[cnt].v=v; edge[cnt].next=head[u]; head[u]=cnt++;}void bfs(int x){ int i; queue<int>q; for(i=head[x];i!=-1;i=edge[i].next) { q.push(edge[i].v); } while(!q.empty()) { int u=q.front(); q.pop(); for(i=head[u];i!=-1;i=edge[i].next) { int v=edge[i].v; if(v!=x) vis[v]++; } } for(i=1;i=2) ans+=vis[i]*(vis[i]-1)/2; }}int main(){ int m, i, j, u, v; scanf("%d%d",&n,&m); ans=0; memset(head,-1,sizeof(head)); cnt=0; while(m--) { scanf("%d%d",&u,&v); add(u,v); } for(i=1;i <br> <br> <p></p> </int></algorithm></set></map></queue></ctype.h></math.h></stdlib.h></cstring></string></cstdio></iostream>
