地址：http://pan.baidu.com/s/1hq03BIO
T1：之前想错了= = f[i]表示前i位，且第i位不选的最小价值 f[i]=min{f[j]+A[i]} ，那么ans=TOT-f[i] n-k<i<n
正着想f[i]=max{f[j-1]+sum[i]-sum[j],f[i-1]}也可以用单调队列维护
#include<set> #include<map> #include<cstdio> #include<cstdlib> #include<cstring> #include<iostream> #include<algorithm> using namespace std; const int N = 100010; typedef long long lld; #define inf 2147483647777777 #define For(i,n) for(int i=1;i<=n;i++) #define Rep(i,l,r) for(int i=l;i<=r;i++) using namespace std; void read(int &v){ char ch=getchar();int num=0; while(ch<'0'||ch>'9') ch=getchar(); while(ch>='0'&&ch<='9') { num=num*10+ch-'0'; ch=getchar(); } v=num; } int n,k,l,r; lld TOT,ans=inf,f[N]; int A[N]; struct queues{ int id;lld v; }q[N]; void init(){ read(n);read(k); For(i,n) read(A[i]),TOT+=A[i]; } void dp(){ For(i,n){ f[i]=A[i]+q[l].v; while(q[r].v>f[i]&&l<=r) r--; q[++r].v=f[i];q[r].id=i; while(q[l].id<i-k) l++; } Rep(i,n-k,n) ans=min(ans,f[i]); printf("%I64d",TOT-ans); } int main(){ freopen("mowlawn.in","r",stdin); freopen("mowlawn.out","w",stdout); init(); dp(); return 0; }
堆版本的，应老师要求写的= =
#include<set>
#include<map>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
const int N = 100010;
typedef long long lld;
typedef pair<lld,int> point;
#define w first
#define id second
#define For(i,n) for(int i=1;i<=n;i++)
#define Rep(i,l,r) for(int i=l;i<=r;i++)
point H[N];
lld ans,TOT;
int L,Loc[N],n,k,A[N];
lld dp[N];
//下调
void Down(int No,point H[]){
int fa=No,son=No*2;
while(son<=L){
if(H[son].w>H[son+1].w&&son<L) {
//swap(Loc[H[son].id],Loc[H[son+1].id]);
son++;
}
if(H[son].w<H[fa].w) {
swap(Loc[H[son].id],Loc[H[fa].id]);
point c=H[son];H[son]=H[fa];H[fa]=c;
}
fa=son;son=fa*2;
}
}
//删除堆元素
void Delete(int No,point H[]){
Loc[H[L].id]=Loc[H[No].id];
H[No]=H[L--];
Down(No,H);
}
//上调
void Up(int No,point H[]){
int fa=L/2,son=L;
while(H[son].w<H[fa].w&&son>1){
swap(Loc[H[son].id],Loc[H[fa].id]);
point c=H[son];H[son]=H[fa];H[fa]=c;
son=fa;fa=son/2;
}
}
void Insert(point NODE,point H[]){
H[++L]=NODE;
Loc[NODE.id]=L;
Up(L,H);
}
void init(){
scanf("%d%d",&n,&k);
For(i,n) scanf("%d",&A[i]),TOT+=A[i];
}
void DP(){
ans=1e18;
Insert(make_pair(0,0),H);
For(i,n){
dp[i]=H[1].w+A[i];
Insert(make_pair(dp[i],i),H);
if(i>k) Delete(Loc[i-k-1],H);
}
For(i,n) cout<<dp[i]<<endl;
Rep(i,n-k,n) ans=(dp[i]<ans)?(dp[i]):(ans);
printf("%I64d
",TOT-ans);
}
int main(){
freopen("mowlawn.in","r",stdin);
freopen("mowlawn.out","w",stdout);
init();
DP();
return 0;
}
T2: 很坑爹的bfs，考场上没看到是一些传送门。。就写了一个传送门的。。。由于增量是1，所以可以不用bfs
1 #include<set> 2 #include<map> 3 #include<cstdio> 4 #include<cstdlib> 5 #include<cstring> 6 #include<iostream> 7 #include<algorithm> 8 using namespace std; 9 const int N = 310; 10 const int dx[5]={0,-1,1,0,0}, 11 dy[5]={0,0,0,-1,1}; 12 typedef pair<pair<int,int>,int> newp; 13 #define x first 14 #define y second 15 #define For(i,n) for(int i=1;i<=n;i++) 16 #define Rep(i,l,r) for(int i=l;i<=r;i++) 17 char maze[N][N]; 18 int x,y,n,m;bool hash[N][N]; 19 newp q[N*3*N]; 20 pair<int,int> two[3],cnt[30][2]; 21 22 void init(){ 23 scanf("%d%d",&n,&m); 24 For(i,n) { 25 scanf("%s",maze[i]+1); 26 For(j,m){ 27 if(maze[i][j]=='@'){x=i;y=j;} 28 if(isupper(maze[i][j])) 29 if(cnt[maze[i][j]-'A'+1][0].first>0) cnt[maze[i][j]-'A'+1][1]=make_pair(i,j); 30 else cnt[maze[i][j]-'A'+1][0]=make_pair(i,j); 31 } 32 } 33 } 34 35 int BFS(){ 36 int l=0,r=1;q[r]=make_pair(make_pair(x,y),0);hash[x][y]=true; 37 while(l<r){ 38 newp head=q[++l]; 39 pair<int,int> First=head.x;int w=head.y; 40 if(maze[First.x][First.y]=='=') return w; 41 For(i,4){ 42 int tx=First.x+dx[i],ty=First.y+dy[i]; 43 if(tx>n||ty>m||tx<=0||ty<=0) continue; 44 if(!hash[tx][ty]&&maze[tx][ty]!='#'){ 45 hash[tx][ty]=true; 46 if(isupper(maze[tx][ty])){ 47 if(cnt[maze[tx][ty]-'A'+1][0]!=make_pair(tx,ty)){ 48 q[++r]=make_pair(cnt[maze[tx][ty]-'A'+1][0],w+1); 49 hash[tx][ty]=false; 50 } 51 else{ 52 q[++r]=make_pair(cnt[maze[tx][ty]-'A'+1][1],w+1); 53 hash[tx][ty]=false; 54 } 55 continue; 56 } 57 q[++r]=make_pair(make_pair(tx,ty),w+1); 58 } 59 } 60 } 61 } 62 63 int main(){ 64 freopen("cornmaze.in","r",stdin); 65 freopen("cornmaze.out","w",stdout); 66 init(); 67 printf("%d ",BFS()); 68 return 0; 69 }