由於評測機的緣故……它unrated了。。c++
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 1005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } int N,K; void Solve() { read(N);read(K); out(N - K + 1);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }
……spa
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 1005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } int R,G,B,N; void Solve() { read(R);read(G);read(B);read(N); int cnt = 0; for(int i = 0 ; i <= N / R ; ++i) { int t = N - i * R; for(int j = 0 ; j <= t / G ; ++j) { int h = N - i * R - j * G; if(h % B == 0) ++cnt; } } out(cnt);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }
丟人選手交了6遍,罰時+++++code
就是記錄BA,和只有前面有B,只有後面有Arem
*A\BA\B*get
這樣三個拼兩個string
而後若是隻剩*A和B*就都配起來it
不然就看一開始是否存在*A和B*,把BA都配起來io
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 1005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } int N; char s[MAXN]; int a[3]; void Solve() { read(N); int ans = 0; for(int i = 1 ; i <= N ; ++i) { scanf("%s",s + 1); int l = strlen(s + 1); for(int j = 1 ; j < l ; ++j) { if(s[j] == 'A' && s[j + 1] == 'B') ++ans; } if(s[1] == 'B' && s[l] == 'A') ++a[2]; else if(s[1] == 'B') ++a[1]; else if(s[l] == 'A') ++a[0]; } int t = min(a[2],min(a[0],a[1])); ans += t * 2; a[2] -= t;a[0] -= t;a[1] -= t; ans += min(a[0],a[1]); if(a[2]) { if(t) ans += a[2]; else if(max(a[0],a[1])) ans += a[2]; else ans += a[2] - 1; } out(ans);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }
\(\lfloor \frac{N}{i} \rfloor\)只有\(\sqrt{N}\)種取值,枚舉出來求出m而後看m在不在對應區間便可class
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 1005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } int64 N; void Solve() { read(N); int64 ans = 0; for(int64 i = 1 ; i <= N ; ++i) { int64 r = N / (N / i); int64 t = N / i; if(N % t == 0) { int64 k = N / t - 1; if(k >= i && k <= r) ans += k; } i = r; } out(ans);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }
若是一段不爲0的話,那麼這些位置的前綴和確定是a0a0a0a0,這樣的話就\(dp[i]\)表示這個數爲結尾,而後找前一段和它相同的\(dp[j]\)且\(s[i] == s[j]\),轉移乘上中間全部的0的個數,能夠經過拆成前綴和分項維護test
最後計算每一段爲0的方案數
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 500005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } int MOD = 1000000007; int N; int A[MAXN],sum[MAXN],s[MAXN]; int pre[2][(1 << 20) + 5],dp[MAXN]; int inc(int a,int b) { return a + b >= MOD ? a + b - MOD : a + b; } int mul(int a,int b) { return 1LL * a * b % MOD; } void update(int &x,int y) { x = inc(x,y); } int fpow(int x,int c) { int res = 1,t = x; while(c) { if(c & 1) res = mul(res,t); t = mul(t,t); c >>= 1; } return res; } void Solve() { read(N); for(int i = 1 ; i <= N ; ++i) { read(A[i]); s[i] = s[i - 1] ^ A[i]; sum[i] = sum[i - 1] + (s[i] == 0); } int all = 0; for(int i = 1 ; i <= N ; ++i) { if(s[i] != 0) { dp[i] = mul(pre[0][s[i]],sum[i - 1]) + 1; update(dp[i],MOD - pre[1][s[i]]); } else dp[i] = inc(all,MOD - pre[0][0]); update(pre[0][s[i]],dp[i]); update(pre[1][s[i]],mul(dp[i],sum[i])); update(all,dp[i]); } if(s[N] == 0) { update(dp[N],fpow(2,sum[N] - 1)); } out(dp[N] % MOD);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }
假如樹邊的大小固定了,那麼非樹邊的必須大於樹邊中最大的那條
若是咱們認爲非樹邊是白球,樹邊是黑球,就是先填被最大的邊控制的白球,而後填最大的黑球,填被次大的邊控制的白球,填次大的黑球……
這個序列應該是來了白球能夠在任意位置,來了黑球必須放到序列最前面
那麼怎麼統計價值和呢,記錄序列長度n,序列種類c,黑球個數b,和價值和s
若是來了一個黑球
\((n,c,b,s)\rightarrow (n + 1,c,b + 1,s + (b +1)c)\)
若是來了一個白球
\((n,c,b,s)\rightarrow(n + 1,c(n +1),b,s(n + 2))\)
爲啥是\(n + 2\)呢。。由於若是把那個白球從前移到後,會發現\(s\)被加了\((n +1)\)次,餘下的零頭是原來全部黑球的座標和
而後若是來了k個白球
\((n,c,b,s) \rightarrow (n + k,c(n + 1)(n + 2)\cdots(n + k),b,s(n + 2)(n + 3)\cdots(n + k + 1))\)
那麼又回到剛開始的假設了,如何肯定樹邊的大小呢
能夠用dp從大到小分配每一個樹邊
設S表示集合爲S的樹邊已經被固定了
每次新加一條樹邊控制的非樹邊,是加以後非樹邊的兩個點連通的非樹邊的個數,減掉加以前非樹邊兩個點連通非樹邊的個數
這個只要對於每一種邊集連起來,而後搜出每一個聯通塊,計算聯通塊之間邊相連的數目再減去聯通塊裏樹邊的數目便可
聯通塊裏邊的數目能夠很容易經過dp算出
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 500005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } const int MOD = 1000000007; int N,M; int a[205],b[205],fac[205],invfac[205]; int col[(1 << 20) + 5][21],num[(1 << 20) + 5],c[21]; int to[21],e[(1 << 20) + 5],cnt[(1 << 20) + 5]; int dp[(1 << 19) + 5],sum[(1 << 19) + 5],len[(1 << 19) + 5]; int fa[21]; int inc(int a,int b) { return a + b >= MOD ? a + b - MOD : a + b; } int mul(int a,int b) { return 1LL * a * b % MOD; } void update(int &x,int y) { x = inc(x,y); } int lowbit(int x) { return x & (-x); } int getfa(int x) { return fa[x] == x ? x : fa[x] = getfa(fa[x]); } int fpow(int x,int c) { int res = 1,t = x; while(c) { if(c & 1) res = mul(res,t); t = mul(t,t); c >>= 1; } return res; } void Solve() { read(N);read(M); for(int i = 1 ; i <= M ; ++i) { read(a[i]);read(b[i]); to[a[i]] |= (1 << b[i] - 1); to[b[i]] |= (1 << a[i] - 1); } fac[0] = 1; for(int i = 1 ; i <= 200 ; ++i) fac[i] = mul(fac[i - 1],i); invfac[200] = fpow(fac[200],MOD - 2); for(int i = 199 ; i >= 0 ; --i) invfac[i] = mul(invfac[i + 1],i + 1); for(int S = 0 ; S < (1 << N) ; ++S) { if(S != 0) cnt[S] = cnt[S - lowbit(S)] + 1; for(int j = 1 ; j <= N ; ++j) { if(S >> (j - 1) & 1) { int T = to[j] & S; e[S] = e[S ^ (1 << j - 1)] + cnt[T];break; } } } for(int S = 0 ; S < (1 << N - 1) ; ++S) { for(int i = 1 ; i <= N ; ++i) fa[i] = i; for(int i = 1 ; i < N ; ++i) { if(S >> (i - 1) & 1) { fa[getfa(a[i])] = getfa(b[i]); } } int tot = 0; for(int i = 1 ; i <= N ; ++i) { if(fa[i] == i) {col[S][i] = ++tot;c[tot] = 0;} } for(int i = 1 ; i <= N ; ++i) { col[S][i] = col[S][getfa(i)]; int t = col[S][i]; c[t] |= (1 << i - 1); } for(int i = 1 ; i <= tot ; ++i) { num[S] += e[c[i]] - (cnt[c[i]] - 1); } } dp[0] = 1;sum[0] = 0; int ALL = (1 << N - 1) - 1; for(int S = 0 ; S < (1 << N - 1) ; ++S) { for(int j = 1 ; j < N ; ++j) { if(!(S >> (j - 1) & 1)) { int a = num[ALL ^ S] - num[ALL ^ S ^ (1 << j - 1)]; int T = S ^ (1 << j - 1); int n = len[S]; len[T] = n + a + 1; int c = mul(dp[S],mul(fac[n + a],invfac[n])); int s = mul(sum[S],mul(fac[n + a + 1],invfac[n + 1])); update(s,mul(c,cnt[S] + 1)); update(dp[T],c);update(sum[T],s); } } } out(sum[(1 << N - 1) - 1]);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }