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
}