链接：

Problem A：

#include 
    
     #include 
     
      #include 
      
       #include 
       
        using namespace std;const int maxn = 222;struct Point{    long long x, y;    Point(long long x = 0, long long y = 0) : x(x), y(y) { }    void read()    {        scanf("%lld %lld", &x, &y);    }};typedef Point Vector;Vector operator - (const Point &A, const Point &B){    return Vector(A.x - B.x, A.y - B.y);}long long Cross(const Vector &A, const Vector &B){    return A.x * B.y - A.y * B.x;}long long Dot(const Vector &A, const Vector &B){    return A.x * B.x + A.y * B.y;}double inter(Point p, Vector v, Point q, Vector w){    Vector u = p - q;    return 1.0 * Cross(w, u) / Cross(v, w);}bool on(Point p, Point a, Point b){    return Cross(p - a, p - b) == 0;}int dcmp(long long x){    if (x == 0)        return 0;    return x > 0 ? 1 : -1;}int n;Point p[maxn];double ans = 0.0;void solve(Point A, Point B){    vector
        
          lst;    for (int i = 0; i < n; ++i)    {        if (dcmp(Cross(p[i] - A, B - A)) * dcmp(Cross(p[i + 1] - A, B - A)) >= 0)            continue;        lst.push_back(inter(A, B - A, p[i], p[i + 1] - p[i]));    }    for (int i = 0; i < n; ++i)    {        if (!on(p[i], A, B))            continue;        Point L = p[(i + n - 1) % n];        Point N = p[(i + 1) % n];        Point P = p[i];        long long dir = Cross(B - A, L - A);        double pos = 1.0 * Dot(P - A, B - A) / Dot(B - A, B - A);        if (dir == 0)        {            if (Dot(B - A, P - L) > 0)            {                if (Cross(B - A, N - A) > 0)                    lst.push_back(pos);            }            else            {                if (Cross(B - A, N - A) < 0)                    lst.push_back(pos);            }        }        else if (dir > 0)        {            if (Cross(B - A, N - A) < 0)                lst.push_back(pos);            else if (Cross(B - A, N - A) == 0 && Dot(B - A, N - P) > 0)                lst.push_back(pos);        }        else        {            if (Cross(B - A, N - A) > 0)                lst.push_back(pos);            else if (Cross(B - A, N - A) == 0 && Dot(B - A, N - P) < 0)                lst.push_back(pos);        }    }    sort(lst.begin(), lst.end());    double len = sqrt(Dot(B - A, B - A));    for (int i = 0; i < (int)lst.size(); i += 2)        ans = max(ans, (lst[i + 1] - lst[i]) * len);}int main(){    scanf("%d", &n);    for (int i = 0; i < n; ++i)        p[i].read();    p[n] = p[0];    for (int i = 0; i < n; ++i)        for (int j = i + 1; j < n; ++j)            solve(p[i], p[j]);    printf("%.10f\n", ans);    return 0;}
        
       
      
     
    

Problem C：

#include 
    
     using namespace std;typedef long long ll;const int N = 305, M = 100005;const ll inf = 1ll << 60;int head[N];struct Edge {    int nxt, to, cow;    ll cost;    Edge() {}    Edge(int nxt, int to, int cow, ll cost) : nxt(nxt), to(to), cow(cow), cost(cost) {}} ed[M];int ecnt, mx_flow;ll mi_cost;void init() {    mx_flow = mi_cost = ecnt = 0;    memset(head, -1, sizeof(head));}void addE(int u, int v, int cow, ll cost) {    ed[ecnt] = Edge(head[u], v, cow, cost);    head[u] = ecnt ++;    ed[ecnt] = Edge(head[v], u, 0, -cost);    head[v] = ecnt ++;}queue 
     
       Q;ll dis[N];int pre[N], inq[N], tot;bool spfa(int S, int T) {    for (int i = 0; i < tot; ++ i)        dis[i] = inf;    dis[S] = 0;    Q.push(S);    while (!Q.empty()) {        int u = Q.front(); Q.pop();        inq[u] = 0;        for (int e = head[u]; ~e; e = ed[e].nxt) {            if (!ed[e].cow)                continue;            int v = ed[e].to;            if (dis[v] > dis[u] + ed[e].cost) {                dis[v] = dis[u] + ed[e].cost;                pre[v] = e;                if (!inq[v]) {                    inq[v] = 1;                    Q.push(v);                }            }        }    }    return dis[T] < 0;}void aug(int S, int T) {    int flow = 1 << 30;    for (int u = T; u != S; u = ed[pre[u] ^ 1].to)        flow = min(flow, ed[pre[u]].cow);    for (int u = T; u != S; u = ed[pre[u] ^ 1].to) {        ed[pre[u]].cow -= flow;        ed[pre[u] ^ 1].cow += flow;        mi_cost += flow * ed[pre[u]].cost;    }    mx_flow += flow;}int A[105][105];int mxr[105], mxc[105];int idr[105], idc[105];int main() {    init();    int n, m;    scanf("%d%d", &n, &m);    long long sum = 0;    for (int i = 0; i < n; ++ i)        for (int j = 0; j < m; ++ j)            scanf("%d", A[i] + j), sum += A[i][j];    for (int i = 0; i < n; ++ i) {        mxr[i] = - (1 << 30);        for (int j = 0; j < m; ++ j)            mxr[i] = max(mxr[i], A[i][j]);    }    for (int j = 0; j < m; ++ j) {        mxc[j] = - (1 << 30);        for (int i = 0; i < n; ++ i)            mxc[j] = max(mxc[j], A[i][j]);    }    tot = 0;    for (int i = 0; i <= n; ++ i)        idr[i] = tot ++;    for (int i = 0; i <= m; ++ i)        idc[i] = tot ++;    int src = tot ++, des = tot ++;    int use = 0;    for (int i = 0; i < n; ++ i)        if (mxr[i])            addE(src, idr[i], 1, - (1 << 30)), ++ use;    for (int i = 0; i < m; ++ i)        if (mxc[i])            addE(idc[i], des, 1, - (1 << 30)), ++ use;    addE(src, idr[n], 1 << 30, 0);    addE(idc[m], des, 1 << 30, 0);    long long ans = 0;    for (int i = 0; i < n; ++ i) {        for (int j = 0; j < m; ++ j) {            if (A[i][j] == 0)                continue;            ++ ans;            if (mxr[i] < mxc[j]) {                addE(idr[i], idc[m], 1, mxr[i] - 1);            } else if(mxr[i] > mxc[j]) {                addE(idr[n], idc[j], 1, mxc[j] - 1);            } else {                addE(idr[i], idc[j], 1, mxr[i] - 1);                addE(idr[i], idc[m], 1, mxr[i] - 1);                addE(idr[n], idc[j], 1, mxr[i] - 1);            }        }    }    while(spfa(src, des))        aug(src, des);    mi_cost += (1ll << 30) * use;    ans += mi_cost;    cout << sum - ans << endl;    return 0;}
     
    

Problem E:

#include
    
     using namespace std;const int maxn = 1005;int n;double t,d[maxn],s[maxn];double check(double x){    double res = 0;    for(int i=0;i
     
      >n>>t;    for(int i=0;i
      
       >d[i]>>s[i];    double l=-1e9,r=1e9;    for(int cas=0;cas<=100;cas++){        double mid = (l+r)/2.0;        if(check(mid)>t)l=mid;        else r=mid;    }    printf("%.12f\n",l);}
      
     
    

Problem F:

#include
    
     using namespace std;const int maxn = 260;long long d[maxn];long long dp[maxn][maxn];long long cal[maxn][maxn];int n,m;int a,b;int main(){    scanf("%d%d",&n,&m);    for(int i=0;i
    

Problem I：

#include
    
     using namespace std;const int maxn = 30;int mp[maxn][maxn];int main(){    int n,m;    scanf("%d%d",&n,&m);    string a,b;    for(int i=0;i
     
      >a>>b;        mp[a[0]-'a'][b[0]-'a']=1;    }    for(int k=0;k<26;k++){        mp[k][k]=1;        for(int i=0;i<26;i++){            for(int j=0;j<26;j++){                if(mp[i][k]&&mp[k][j])                    mp[i][j]=1;            }        }    }    string s1,s2;    for(int i=1;i<=m;i++){        cin>>s1>>s2;        if(s1.size()!=s2.size()){            cout<<"no"<