2016"百度之星" - 资格赛（Astar Round1）

A题

我用线段树进行处理，但是好像有错误，不过后来数据进行了修改

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define mid (L+R)/2
#define lson o<<1, L, mid
#define rson o<<1|1, mid+1, R
const int maxn = 100500;
const int MOD = 9973;
int cnt[maxn<<2];
int a[maxn];
char s[maxn];

void pushup(int o){
cnt[o] = (cnt[o<<1]*cnt[o<<1|1])%MOD;
}

void build(int o,int L,int R)
{
if(L == R)
{
cnt[o] = a[L];
return ;
}
build(lson);
build(rson);
pushup(o);
}

int query(int o,int L,int R,int x,int y)
{
if(x <= L && R <= y)
return cnt[o];
int ret = 1;
if(x <= mid)
ret = (ret*query(lson,x,y))%MOD;
if(y > mid)
ret = (ret*query(rson,x,y))%MOD;
return ret;
}

int main()
{
int N;
while(scanf("%d", &N) != EOF)
{
scanf("%s", s);
int len = strlen(s);
for(int i = 0; i < len; i++)
a[i+1] = s[i] - 28;
build(1, 1, len);
int a,b,temp;
for(int i = 0; i < N; i++)
{
scanf("%d%d", &a, &b);
if(a > b||a < 1||b < 1||b > len ||a > len)
printf("%d\n", temp);
else
{
temp = query(1,1,len,a,b);
printf("%d\n", temp);
}
}
}
return 0;
}

B题

处理一下高精度加法，用数组存一下，可以看成上楼梯，每次上一层或者2层，于是可以总结出f[i] = f[i-1]+f[i-2].

#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;
const int maxn = 1005;
int a[maxn][maxn];

void init(int a[maxn][maxn])
{
memset(a,0,sizeof(a));
a[1][0] = 1;
a[2][0] = 2;
for(int i = 3; i <= 1002; i++)
{
for(int j = 0; j < maxn ; j++)
{
a[i][j] += a[i-1][j] + a[i-2][j];
if(a[i][j] >= 10)
{
a[i][j] -= 10;
a[i][j+1]++;
}
}
}
}

int main()
{
int n,i;
init(a);
while(scanf("%d", &n) != EOF)
{
for(i = 1000; i >= 0; i--)
if(a
[i]) break;
for(; i >= 0; i--)
printf("%d",a
[i]);
printf("\n");
}
return 0;
}

C题

字典树的题目，有时会漏一些情况，一种情况是，加了往字典树加he，hee，heee，heeee，删除hee后，查看he和h是否存在，另一种情况就是插入hee，hello，heee，删除hee，查看he和hell是否存在。

#include <cstdio>
#include <cstring>
#include <iostream>
#include <stack>
using namespace std;
const int maxnode = 3000000;
const int sigma_size = 27;

struct Node
{
int x,y;
Node(int a,int b):x(a),y(b){}
Node() {}
};

struct Trie
{
int ch[maxnode][sigma_size];
int val[maxnode];
int sz;
Trie() {sz = 1; memset(ch[0], 0, sizeof(ch[0]));}
int idx(char c) {return c - 'a';}
void Insert(char *s)
{
int u = 0, n = strlen(s);
for(int i = 0; i < n; i++)
{
int c = idx(s[i]);
if(!ch[u][c])
{
memset(ch[sz], 0, sizeof(ch[sz]));
val[sz] = 1;
ch[u][c] = sz++;
u = ch[u][c];
}
else
{
u = ch[u][c];
val[u]++;
}
}
}

bool Search(char *s)
{
int u = 0,n = strlen(s);
for(int i = 0; i < n; i++)
{
int c = idx(s[i]);
if(!ch[u][c])
return false;
else u = ch[u][c];
}
return true;
}

void Delete(char *s)
{
stack <Node> S;
while(!S.empty()) S.pop();
int u = 0,n = strlen(s),f,c;
for(int i = 0; i < n; i++)
{
c = idx(s[i]);
S.push(Node(u,c));
if(!ch[u][c])
return;
else
{
f = u;
u = ch[u][c];
}
}
ch[f][c] = 0;
if(val[f] - val[u] == 0)
{
S.pop();
while(!S.empty())
{
Node node = S.top();
S.pop();
int temp = ch[node.x][node.y];
//               printf("%d %d\n", node.x,node.y);
if(val[temp] - val[u]) break;
else ch[node.x][node.y] = 0;
}
}
}
};

Trie tree;

int main()
{
int N;
scanf("%d", &N);
char op[10],s[35];
while(N--)
{
scanf("%s %s", op, s);
if(op[0] == 'i')
tree.Insert(s);
else if(op[0] == 's')
{
if(tree.Search(s)) printf("Yes\n");
else printf("No\n");
}
else if(op[0] == 'd')
tree.Delete(s);
}
return 0;
}

D题

仅仅是用STL中的map就可以解出来了

#include <cstdio>
#include <string>
#include <cstring>
#include <iostream>
#include <map>
#include <algorithm>
using namespace std;
const int maxn = 100005;
int has[maxn];
string str;
map <string, int> Map;

int main()
{
int N;
scanf("%d", &N);
while(N--)
{
cin >> str;
sort(str.begin(), str.end());
if(Map[str])
{
printf("%d\n", Map[str]);
Map[str]++;
}
else
{
printf("0\n");
Map[str] = 1;
}
}
return 0;
}