PAT 1046-1057

本文提供了PAT-A级编程竞赛中的11道题目的详细解答,包括Shortest Distance、Student List for Course、Find Coins等,涉及算法如DFS、树状数组等,通过实际代码示例帮助读者理解解题思路。

摘要生成于 C知道 ,由 DeepSeek-R1 满血版支持, 前往体验 >


1046. Shortest Distance(20)

原题地址:http://www.patest.cn/contests/pat-a-practise/1046

解题思路:无他。求距离的题目,最好选一个参考点保存各节点的位置,这样两节点间的距离由位置差即可求得。

代码如下:
#include <cstdio>
#include <cstring>
#define MAXN 100005

int dist[MAXN];
int TD;

int N, M;

int main(){
//  freopen("1046.txt","r",stdin);
  TD = 0;
  memset(dist,0,sizeof(dist));
  scanf("%d",&N);
  for(int i = 0; i < N; i++) {scanf("%d",dist+i+1); TD += dist[i+1]; dist[i+1] = TD;}  
  scanf("%d",&M);
  
  for(int i = 0; i < M; i++){
    int f, t;
    scanf("%d%d",&f,&t);
    if(f > t) { int tm = t; t = f; f = tm;}
//    int dm = 0;
    if(dist[t-1] - dist[f-1] <= TD + dist[f-1] - dist[t-1]) printf("%d\n",dist[t-1] - dist[f-1]);
    else printf("%d\n",TD + dist[f-1] - dist[t-1]);
//    printf("%d,%d,%d\n",TD,dist[f-1],dist[t-1]);
  }
  return 0;
}

1047. Student List for Course (25)

原题地址:http://www.patest.cn/contests/pat-a-practise/1047

解题思路:用vector保存每门课的学生名单即可。

代码如下:
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#define MAXK 2505
using namespace std;

vector<string> co[MAXK];

int N,K;

int main(){
//  freopen("1047.txt","r",stdin);
  scanf("%d%d",&N,&K);
  for(int i = 0; i < N; i++){
    char name[8];
    int c;
    scanf("%s%d",name,&c);
    string n(name);
    for(int i = 0; i < c; i++){
      int t;
      scanf("%d",&t);
      co[t].push_back(n);
    }
  }
  for(int i = 1; i <= K; i++){
    int m = co[i].size();
    printf("%d %d\n",i,m);
    if(m != 0){
      sort(co[i].begin(),co[i].end());
      for(int j = 0; j < m; j++) printf("%s\n", co[i][j].c_str());
    }
  }
}

1048. Find Coins (25)

解题思路:开数组记录不同面值银币的个数,再从头往后找符合的组合即可。

原题地址:http://www.patest.cn/contests/pat-a-practise/1048

代码如下:
#include <cstdio>
#include <cstring>

#define MAXN 1010

int cou[MAXN];
int N, M;
int main(){
//  freopen("1048.txt","r",stdin);
  memset(cou,0,sizeof(cou));
  scanf("%d%d",&N,&M);
  
  for(int i = 0 ; i < N; i++){
    int co;
    scanf("%d",&co);
    cou[co]++;
  }  
  
  for(int i = 1 ; i <= 500 ; i++){
    if( i*2 < M && cou[i] > 0 && cou[M-i] >0){
      printf("%d %d",i,M-i);
      return 0;
    }else if( i*2 == M && cou[i] > 1){
      printf("%d %d", i, i);
      return 0;
    }
  }
  
  printf("No Solution");
  return 0;

}

1049. Counting Ones (30)

原题地址:http://www.patest.cn/contests/pat-a-practise/1049

解题思路:我的思路比较蠢,将数字切分成整十整百整千部分考虑,比较繁琐。
注:(网上有好的方法,即考虑每一位上1出现的个数,找出规律,过程简洁明了。具体可参考:http://blog.youkuaiyun.com/tiantangrenjian/article/details/19908885)

代码如下:
#include <cstdio>
#include <cmath>

int N;
int cou;


int generate(int m){
  int co = 0;
  for(int i = 0; i < m; i++){ 
    co = pow(10,i) + 10*co;
  }
//  printf("%d,return gene: %d\n",m,co);  
  return co;
}

int count(int n){
//  printf("n:%d\n",n);
  int m = 0;
  int tmp = n;
  int co = 0;
  for(; m <= 9 ;m++){
    if(tmp/10 == 0) break;
    tmp /= 10;
  }
  
//  printf("tmp:%d\n",tmp);
  
  if(tmp > 1) co += ( pow(10,m) +  count(n - tmp*pow(10,m)) + (tmp) * generate(m));
  else if(tmp == 1)  co += (n - tmp*pow(10,m) + 1 + count(n - tmp*pow(10,m)) + generate(m));
    
//    printf("count %d: %d\n", n, co);
    return co;
}

int main(){
  
  scanf("%d",&N);
  
  cou = count(N);
  
  printf("%d\n",cou);
  
  return 0;
}

1050. String Subtraction (20)


原题地址:http://www.patest.cn/contests/pat-a-practise/1050

解题思路:记录s2中每个字符出现与否。我的坑点在于,一开始将strlen()函数写进循环判断,导致超时。

代码如下:
#include <cstdio>
#include <cstring>
#define MAXN 10010

char data[MAXN];
char ab[MAXN];
int flag[100];

int main(){
//  freopen("1050.txt","r",stdin);
  gets(data);
  memset(flag,0,sizeof(flag));
  gets(ab);
//  int cou = 0;
  int l = strlen(ab);
  for(int i = 0; i < l; i++){
    int id = ab[i] - ' ';
//    if(flag[id] == 0) cou++;
    flag[id] = 1;
  }  
//  printf("%s",data);
  l = strlen(data); 
  for(int i = 0; i < l; i++){
    char c = data[i];
    if(!flag[c-' ']) printf("%c",c);
  }
  return 0;
}

1051. Pop Sequence (25)

原题地址:http://www.patest.cn/contests/pat-a-practise/1051

解题思路:用stack保存过渡栈内容。。

代码如下:
#include <cstdio>
#include <algorithm>
#include <stack>
#define MAXN 1005
using namespace std;

stack<int> st;
int sq[MAXN];

int M, N, K;

void clear(){
  while(!st.empty()) st.pop();  
}

int isPop(){
  int co = 0;
  clear();
  for(int i = 0; i < N; i++){
    if(st.size() < M && i+1 == sq[co]){
      co++;
//      printf("sq[%d]:%d\n",co,sq[co]);
      
//      if(!st.empty()) printf("st:%d\n",st.top());
    
      while(!st.empty() && st.top() == sq[co]){
        co++;
        st.pop();
      }
    }else if(st.size() < M) st.push(i+1);
    else return 0;  
  }
  if(st.empty())
    return 1;
  else return 0;  
  
}

int main(){
//  freopen("1051.txt","r",stdin);
  scanf("%d%d%d",&M,&N,&K);
  for(int i = 0; i < K; i++){
    for(int j = 0; j < N; j++){
      scanf("%d",sq+j);
    }
    
    if(isPop()) printf("YES\n");
    else printf("NO\n");  
  }  
}

1052. Linked List Sorting (25)

原题地址:http://www.patest.cn/contests/pat-a-practise/1052

解题思路:读入链表元素,进行排序。注意节点的指向下一地址。

代码如下:
#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>
#define MAXN 100005
using namespace std;


typedef struct{
  int add;
  int val;
  int nest;
}node;


vector<node> vn;
node n[MAXN];
int val[MAXN];
int nest[MAXN];
int N, sadd;


int cmp(const node n1, const node n2){
  return n1.val < n2.val;
}


int main(){
//  freopen("1052.txt","r",stdin);
  
  memset(nest,-1,sizeof(nest));
  scanf("%d%d",&N,&sadd);
  
  for(int i = 0; i < N; i++){
    int s,v,t;
    scanf("%d%d%d",&s,&v,&t);
    nest[s] = t;
    val[s] = v;  
  }
  int s = sadd;
  int cou = 0;
  while(s!=-1){
    n[s].add = s;
    n[s].val = val[s];
    n[s].nest = nest[s];
    vn.push_back(n[s]);
    s = nest[s];
    cou++;
  }
  
  sort(vn.begin(),vn.end(),cmp);  
  
  if(cou > 0)
    printf("%d %.5d\n", cou,vn[0].add);  
  else 
    printf("0 -1");
  
  for(int i = 0; i < cou-1; i++){
    printf("%.5d %d %.5d\n", vn[i].add, vn[i].val, vn[i+1].add);
  }
  if(cou > 0)
    printf("%.5d %d %d\n", vn[cou-1].add, vn[cou-1].val, -1);
  return 0;
}

1053. Path of Equal Weight (30)

原题地址:http://www.patest.cn/contests/pat-a-practise/1053

解题思路:dfs+回溯即可。

代码如下:
#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>
using namespace std;
#define MAXN 105

int chd[MAXN][MAXN];
int val[MAXN];
int isFa[MAXN];
vector<vector<int> > route;
vector<int> ro;
int N, M, S;
int curm;

int cmp(const vector<int> v1, const vector<int> v2){
  int m = v1.size();
  if(m > v2.size()) m = v2.size();
  for(int i = 0; i < m; i++){
    if(v1[i] == v2[i]) continue;
    else return v1[i] > v2[i];  
  }
  
  return 0;
}

int find(int root){
  ro.push_back(val[root]);
  curm += val[root];
  if(curm == S && !isFa[root]){ 
    vector<int> v;
    v.assign(ro.begin(),ro.end());
    route.push_back(v);
  }else  if(curm < S){
    for(int i = 0; i < N; i++){
      if(chd[root][i])
        find(i);
    }  
  }
  ro.pop_back();
  curm -= val[root];  
  return 0;
}

int main(){
//  freopen("1053.txt","r",stdin);
  
  memset(chd,0,sizeof(chd));
  memset(val,0,sizeof(val));
  memset(isFa,0,sizeof(isFa));
  scanf("%d%d%d",&N, &M, &S);
  for(int i = 0; i < N; i++) scanf("%d",val+i);
  for(int i = 0; i < M; i++){
    int id,num;
    scanf("%d%d",&id,&num);
    isFa[id] = 1;
    for(int j = 0; j < num; j++){
      int c;
      scanf("%d",&c);
      chd[id][c] = 1;
    }
  }
  int root = 0;  
  curm = 0;
  find(root);
  sort(route.begin(),route.end(),cmp);
  for(int i = 0; i < route.size(); i++){
    vector<int> v = route[i];
    int flag = 1;
    for(int j = 0; j < v.size(); j++){
      if(flag) flag = 0;
      else printf(" ");
      printf("%d", v[j]);
    }
    printf("\n");  
  }
}

1054. The Dominant Color (20)

原题地址:http://www.patest.cn/contests/pat-a-practise/1054

解题思路:直接遍历找出现最多的元素也能ac。
(注:说一下巧妙的解法: 首先用num 和 count 分别来保存出现最多的数和次数。每次读入一个数,若 count 等于0,则将num赋值读入的数,count ++; 否则,若读入的数与num相等,count++,若读入的数与num 不同,则count--; 这样最后保存的额num一定是出现次数大于一半的那个数。)

代码如下:
#include <cstdio>
#include <cstring>
#include <algorithm>
#define MAXN 805*605
using namespace std;

int data[MAXN];
int M,N;

int main(){
//  freopen("1054.txt","r",stdin);
  scanf("%d%d",&M,&N);
  for(int i = 0; i < M*N; i++) scanf("%d",data+i);
  
  sort(data,data+M*N);
  
  printf("%d\n",data[M*N/2]);
}

1055. The World's Richest (25)

原题地址:http://www.patest.cn/contests/pat-a-practise/1055

解题思路:用stl中的sort即可。

代码如下:
#include <cstdio>
#include <algorithm>
#include <cstring>
#define MAXN 100005
using namespace std;

typedef struct{
  char name[10];
  int age;
  int worth;
}person;

person p[MAXN];

int N,K;

int cmpN(const char* a, const char *b){
  int lena = strlen(a);  
  int lenb = strlen(b);
  for(int i = 0; i < lena && i < lenb; i++){
    if(a[i] == b[i]) continue;
    else return a[i] < b[i];  
  }
  
  return lena > lenb;
}

int cmp(const person p1, const person p2){
  if(p1.worth == p2.worth){
    if(p1.age == p2.age) return cmpN(p1.name, p2.name);
    else return p1.age < p2.age;  
  }
  else return p1.worth > p2.worth;
}

int main(){
//  freopen("1055.txt","r",stdin);
  scanf("%d%d",&N,&K);
  for(int i = 0; i < N; i++){
    scanf("%s%d%d",p[i].name,&p[i].age,&p[i].worth);
  }
  
  sort(p,p+N,cmp);
  
  for(int i = 0; i < K; i++){
    printf("Case #%d:\n", i+1);
    int m,f,t;
    scanf("%d%d%d",&m,&f,&t);
    int flag = 1; 
    int index = 0;
    while(m>0 && index < N){
      if(p[index].age >= f && p[index].age <= t){
        m--;
        printf("%s %d %d\n", p[index].name, p[index].age, p[index].worth);
        flag = 0;
      }
      index++;  
    }
    if(flag) printf("None\n");  
  }
}

1056. Mice and Rice (25)

原题地址:http://www.patest.cn/contests/pat-a-practise/1056

解题思路:下一回合晋级人数+1即为当前排名。

代码如下:
#include <cstdio>
#include <queue>
#include <cstring>
#define MAXN 1005
using namespace std;

queue<int> q1;
queue<int> q2;

int data[MAXN];
int order[MAXN];
int rak[MAXN];

int Np,Ng;

int main(){
  
//  freopen("1056.txt","r",stdin);
  
  scanf("%d%d",&Np,&Ng);
  memset(rak,0,sizeof(rak));
  
  for(int i = 0; i< Np; i++) scanf("%d",data+i);
  for(int i = 0; i< Np; i++) {scanf("%d",order+i); q1.push(order[i]);}   
  
  int flag = 1;
  
//  printf("%d:%d\n",Np,Ng);
  while(!q1.empty() || !q2.empty()){
     if(flag){
       int a[Ng];
       int mx = -1;
       int indx = -1;
       int co = 0;
       int si = q1.size();
       int rk = si/Ng + (si%Ng > 0) + 1;
       if(si == 1){
         rak[q1.front()] = 1;
         break;  
       }
   
       for(int i = 0; i < si; i++){
         co++;
         a[co-1] = q1.front();
         rak[a[co-1]] = rk;
         
         q1.pop();
         
         if(mx < data[a[co-1]]) { mx = data[a[co-1]]; indx = a[co-1];}
         
         if( co == Ng ){
           co = 0;
           q2.push(indx);
           indx = -1;
           mx = -1;
         }  
       }
       for(int i = 0; i < co; i++){
         rak[a[i]] = rk;
         if(mx < data[a[i]]) { mx = data[a[i]]; indx = a[i];}    
       }
       if(indx > -1) q2.push(indx);
       flag = 0;
     }else{
       int a[Ng];
       int mx = -1;
       int indx = -1;
       int co = 0;
       int si = q2.size();
       int rk = si/Ng + (si%Ng > 0) + 1;
       if(si == 1){
         rak[q2.front()] = 1;
         break;  
       }
       for(int i = 0; i < si; i++){
         co++;
         a[co-1] = q2.front();
         rak[a[co-1]] = rk;
         
         q2.pop();
         
         if(mx < data[a[co-1]]) { mx = data[a[co-1]]; indx = a[co-1];}
         
         if( co == Ng ){
           co = 0;
           q1.push(indx);
           indx = -1;
           mx = -1;
         }  
       }
       for(int i = 0; i < co; i++){
         if(mx < data[a[i]]) { mx = data[a[i]]; indx = a[i];}  
         rak[a[i]] = rk;  
       }
       if(indx > -1) q1.push(indx);
       flag = 1;
     } 
  }
  int fg = 1;  
  for(int i = 0; i < Np; i++){
    if(fg) fg = 0;
    else printf(" ");
    printf("%d", rak[i]);  
  }
  
  return 0;

}

1057. Stack (30)

原题地址:http://www.patest.cn/contests/pat-a-practise/1057

解题思路:用树状数组来找中值。 (加上二分查找会更快。)

代码如下:
#include <cstdio>
#include <algorithm>
#include <vector>
#include <cstring>
#define MAXN 100005
using namespace std;

int st[MAXN];
int mdt[MAXN];
int sz;
int N;

int getSum(int i){
  int s = 0;
  while(i > 0){
    s += mdt[i];
    i -= i&(-i);
  }
  return s;  
}

int query(int l, int h){
  if(l == h) return l;
  int m = (l+h)/2;
  if(getSum(m) < (sz+1)/2) return query(m+1,h);
  else return query(l,m);
}

void update(int i, int value){
  while(i < MAXN){
    mdt[i] += value;
    i += i&(-i);
  }  
}

void doPop(){
  if(sz == 0) printf("Invalid\n");
  else{
    printf("%d\n",st[sz-1]);
    update(st[sz-1],-1);
    sz--;
  }
}

void doPeek(){
  if(sz == 0) printf("Invalid\n");
  else{
    printf("%d\n",query(1,MAXN-1));
  }
}

void doPush(int n){
  st[sz] = n;
  update(n,1);
  sz++;
}
  

int main(){
//  freopen("1057.txt","r",stdin);
  
  sz = 0;
  memset(mdt,0,sizeof(mdt));
  scanf("%d",&N);
  
  for(int i = 0; i < N; i++){
    char s[15];
    scanf("%s",s);
    if(s[1] == 'o') doPop();
    else if(s[1] == 'e') doPeek();
    else{
      int n;
      scanf("%d",&n);
      doPush(n);  
    }
  }
  return 0  
}



评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值