咱們挑出來4的倍數和不是4的倍數而是2的倍數,和奇數c++
而後就是放一個奇數,放一個4,若是一個奇數以後沒法放4,而後它又不是最後一個,那麼就不合法ui
#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 MAXN 100005 #define eps 1e-12 //#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,a[MAXN]; vector<int> v[5],ans; void Solve() { read(N); for(int i = 1 ; i <= N ; ++i) read(a[i]); for(int i = 1 ; i <= N ; ++i) { if(a[i] % 4 == 0) v[4].pb(a[i]); else if(a[i] % 2 == 0) v[2].pb(a[i]); else v[1].pb(a[i]); } while(v[1].size()) { ans.pb(v[1].back()); v[1].pop_back(); if(ans.size() == N) break; if(v[4].size()) { ans.pb(v[4].back()); v[4].pop_back(); } else { puts("No");return; } } puts("Yes"); } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); }
就是每行填,若是填到末尾,就下一行從末尾開始填spa
若是填到開頭,下一行從開始填code
#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 MAXN 100005 #define eps 1e-12 //#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 H,W,N; int a[100005],c[105][105],g[105]; void Solve() { read(H);read(W); read(N); for(int i = 1 ; i <= N ; ++i) read(a[i]); int f = 0; int t = 1; for(int i = 1 ; i <= N ; ++i) { if(g[t] + a[i] < W) { if(!f) { for(int j = g[t] + 1 ; j <= g[t] + a[i] ; ++j) c[t][j] = i; } else { for(int j = W - g[t] ; j >= W - g[t] - a[i] + 1 ; --j) c[t][j] = i; } g[t] += a[i]; } else { for(int j = 1 ; j <= W ; ++j) { if(!c[t][j]) c[t][j] = i; } a[i] -= W - g[t]; if(c[t][W] == i) f = 1; else f = 0; ++t; while(a[i]) { if(!f) c[t][g[t] + 1] = i; else c[t][W - g[t]] = i; ++g[t];--a[i]; if(g[t] == W) ++t; } } } for(int i = 1 ; i <= H ; ++i) { for(int j = 1 ; j <= W ; ++j) { out(c[i][j]);space; } enter; } } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); }
對於一個序列,咱們取一個最小的奇數位置,而後取這個最小的奇數後面的偶數位置,用st表實現,序列會被分紅三份,而後遞歸會造成樹,咱們求一個最小的dfs序便可遞歸
#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 MAXN 200005 #define eps 1e-12 //#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,p[MAXN],tot; int st[2][MAXN][19],len[MAXN],pos[MAXN]; pii t[MAXN]; vector<int> son[MAXN]; set<pii > S; int query_min(int k,int l,int r) { int s = len[r - l + 1]; return min(st[k][l][s],st[k][r - (1 << s) + 1][s]); } int build_tree(int l,int r) { if(r < l) return 0; int k = (l & 1); int a = query_min(k,l,r); int b = query_min(k ^ 1,pos[a] + 1,r); t[++tot] = mp(a,b); int res = tot; son[res].pb(build_tree(l,pos[a] - 1)); son[res].pb(build_tree(pos[a] + 1,pos[b] - 1)); son[res].pb(build_tree(pos[b] + 1,r)); return res; } void Solve() { read(N); for(int i = 1 ; i <= N ; ++i) { read(p[i]); st[i & 1][i][0] = p[i]; st[(i & 1) ^ 1][i][0] = 0x7fffffff; pos[p[i]] = i; } for(int k = 0 ; k <= 1 ; ++k) { for(int j = 1 ; j <= 18 ; ++j) { for(int i = 1 ; i <= N ; ++i) { if(i + (1 << j) - 1 > N) break; st[k][i][j] = min(st[k][i][j - 1],st[k][i + (1 << j - 1)][j - 1]); } } } for(int i = 2 ; i <= N ; ++i) { len[i] = len[i / 2] + 1; } int rt = build_tree(1,N); S.insert(mp(t[rt].fi,rt)); while(!S.empty()) { auto b = *S.begin();S.erase(S.begin()); out(t[b.se].fi);space;out(t[b.se].se);space; for(auto k : son[b.se]) { if(k) S.insert(mp(t[k].fi,k)); } } } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); }
把每一個數改爲異或差分ip
而後修改一個區間至關於修改兩個點,不須要加額外的點,咱們須要把全部異或差分值爲1的地方兩兩配對get
若是相差爲質數,那麼花費爲1it
相差爲偶數 花費爲2class
相差爲奇數且非質數,花費爲3(一個偶數能夠拆成兩個奇素數的和,怎麼地這麼小的範圍總得成立吧,否則哥德巴赫猜測早證僞了,而後只須要挑一個大一點的奇素數減掉這個偶數就好了)sed
以後咱們把這些點分爲奇數點和偶數點,差值爲質數則連邊,作一個最大匹配,以後每一個點集兩兩匹配,若是兩個點集還剩一個,就連一條長度爲3的邊
#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 MAXN 200005 #define eps 1e-12 //#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; bool nonprime[10000005],vis[10000005]; int prime[10000005],tot,x[205],b[205],M[2],matc[205]; vector<int> to[505]; bool used[205]; bool match(int u) { for(auto t : to[u]) { if(!used[t]) { used[t] = 1; if(!matc[t] || match(matc[t])) { matc[t] = u; return true; } } } return false; } void Solve() { read(N); for(int i = 1 ; i <= N ; ++i) { read(x[i]); vis[x[i]] = 1; } for(int i = 2 ; i <= 10000000 ; ++i) { if(!nonprime[i]) { prime[++tot] = i; } for(int j = 1 ; j <= tot ; ++j) { if(prime[j] > 10000000 / i) break; nonprime[i * prime[j]] = 1; if(i % prime[j] == 0) break; } } tot = 0; for(int i = 1 ; i <= 10000001 ; ++i) { if(vis[i] != vis[i - 1]) b[++tot] = i; } for(int i = 1 ; i <= tot ; ++i) { M[b[i] & 1]++; for(int j = 1 ; j <= tot ; ++j) { if(i == j) continue; if(abs(b[i] - b[j]) < 3) continue; if(!nonprime[abs(b[i] - b[j])]) to[i].pb(j); } } int ans = 0; for(int i = 1 ; i <= tot ; ++i) { if(b[i] & 1) { memset(used,0,sizeof(used)); if(match(i)) ++ans; } } out(ans + ((M[0] - ans) / 2 + (M[1] - ans) / 2) * 2 + ((M[0] - ans) & 1) * 3);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); }