2019年全国高校计算机能力挑战赛 C语言程序设计决赛
毕竟这个比赛是第一次举办，能理解。。
希望未来再举办时，能够再完善一下题面表述、数据范围。
话说区域赛获奖名额有点少吧。舍友花60块想混个创新创业分也太难。。
水进了决赛圈，一共6题。
前4题，大概C语言课后习题的难度？
第5题，贪心排个序就好了吧
第6题，图论，拓扑排序，但我用暴力的，因为不知道范围呀，希望能骗点分。
第1题
#include<stdio.h>
const int maxn = 10050;
char s[maxn];
int cnt[5];
int main(){
char c;
int pos = 0;
while((c = getchar()) != EOF){
s[pos++] = c;
}
for(int i=0;i<pos;i++){
if(s[i] == '+') cnt[1]++;
else if(s[i] == '-') cnt[2]++;
else if(s[i] == '*') cnt[3]++;
else if(s[i] == '/') cnt[4]++;
}
printf("+ %d
",cnt[1]);
printf("- %d
",cnt[2]);
printf("* %d
",cnt[3]);
printf("/ %d
",cnt[4]);
return 0;
}
第2题
#include<stdio.h>
const int maxn = 450;
int n;
int a[maxn][maxn];
int main(){
scanf("%d",&n);
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
scanf("%d",&a[i][j]);
}
}
int cnt = 0;
for(int i=1;i<=n;i++){
if(a[i][i] > 0)
cnt++;
}
for(int i=1;i<=n;i++){
int pos = n-i+1;
if(pos == i) continue;
else{
if(a[i][pos] > 0)
cnt++;
}
}
printf("%d",cnt);
return 0;
}
/*
4
1 2 3 4
5 6 7 8
9 0 0 12
1 0 0 -16
*/
第3题
#include<stdio.h>
typedef long long ll;
const int maxn = 1010;
int n;
ll a[maxn];
ll b[maxn];
int main(){
scanf("%d",&n);
bool flag = true;
for(int i=1;i<=n;i++){
scanf("%ld",&a[i]);
int temp = a[i];
int min_x = 9;
while(temp){
if(temp%10 < min_x) min_x = temp%10;
temp /= 10;
}
ll new_num;
if(a[i] == 0){
new_num = a[i];
b[i] = new_num;
flag = false;
}else{
ll new_num = (a[i]/100*10+min_x)*10+min_x;
b[i] = new_num;
if(b[i] == a[i]) flag = false;
}
}
if(flag == true){
printf("Done");
for(int i=1;i<=n;i++) printf(" %ld",b[i]);
}else{
printf("Error");
for(int i=1;i<=n;i++) {
if(b[i] == a[i]) printf(" %ld",b[i]);
}
}
return 0;
}
/*
4
321 96 5 232
3
0 9 322
*/
第4题
#include<stdio.h>
const int maxn = 10010;
char s[maxn];
char ans[maxn];
int pos = 0;
void solve(int start,int ends){
for(int i=start;i<ends;i++){
for(int j=start+1;j<ends;j++){
if((s[i] >= 'A' && s[i] <= 'Z') || (s[i] >= 'a' && s[i] <= 'z')){
if((s[j] >= 'A' && s[j] <= 'Z') || (s[j] >= 'a' && s[j] <= 'z')){
if(s[i] == (s[j] + 1) || s[i] == (s[j] - 1)){
ans[pos++] = ' ';
for(int j=start;j<ends;j++){
ans[pos++] = s[j];
}
return;
}
}
}
}
}
}
int main(){
// freopen("out.txt","w",stdout);
char c;
int start = 0;
int ends = 0;
while((c = getchar()) != EOF){
s[ends++] = c;
if(c == '.'){ //处理最后一个
solve(start,ends-1);
break;
}
if(c == ' '){
solve(start,ends-1);
start = ends;
}
}
if(pos == 0) printf("Accept!");
else{
for(int i=1;i<pos;i++) printf("%c",ans[i]);
}
return 0;
}
/*
There is nothing can stop us from hard working.
nothing stop working
hi st
There is a cat in the box.
*/
第5题
#include<stdio.h>
const int maxn = 10010;
int n;
int a[maxn];
int b[maxn];
int qusort(int s[],int start,int end)
{
int i,j;
i=start;
j = end;
s[0]=s[start];
while(i<j)
{
while(i<j&&s[0]<s[j])
j--;
if(i<j)
{
s[i]=s[j];
i++;
}
while(i<j&&s[i]<=s[0])
i++;
if(i<j)
{
s[j]=s[i];
j--;
}
}
s[i]=s[0];
if (start<i)
qusort(s,start,j-1);
if (i<end)
qusort(s,j+1,end);
return 0;
}
int main(){
scanf("%d",&n);
for(int i=1;i<=n;i++){
scanf("%d",&a[i]);
}
for(int j=1;j<=n;j++){
scanf("%d",&b[j]);
}
qusort(a,1,n);
qusort(b,1,n);
int pos = 1;
int cnt = 0;
for(int i=1;i<=n;i++){
if(a[i] > b[pos]){
cnt++;
pos++;
}
}
printf("%d",cnt);
return 0;
}
/*
6
2 13 26 33 45 9
3 8 30 15 18 40
*/
第6题
dfs暴力找最长的拓扑路径
#include<stdio.h>
const int maxn = 400;
int g[maxn][maxn];
int n;
int a[maxn];
int ans = 0;
int in[maxn];
int out[maxn];
int c;
void dfs(int x,int cur){
if(x == c){
if((cur-a[c]) > ans) ans = cur-a[c];
return;
}
for(int i=1;i<=n;i++){
if(i == x) continue;
if(i!=c && out[i] == 0) continue;
if(g[x][i] == 1){
dfs(i,cur+a[i]);
}
}
}
int main(){
scanf("%d",&n);
for(int i=1;i<=n;i++){
scanf("%d",&a[i]);
}
int u,v;
while(scanf("%d%d",&u,&v) && u!=-1 && v!=-1){
if(g[u][v] == 0){
g[u][v] = 1;
in[v]++;
out[u]++;
}
}
scanf("%d",&c);
if(in[c] == 0) printf("0");
else{
for(int i=1;i<=n;i++){
if(i == c) continue;
if(out[i] == 0) continue;
dfs(i,a[i]);
}
printf("%d",ans);
}
return 0;
}
/*
4
8 12 16 10
1 2
2 3
4 2
1 3
-1 -1
3
3
8 12 16
1 2
1 3
-1 -1
3
*/
队友用拓扑排序做的
#include<iostream>
#include<stack>
#include<vector>
#include<algorithm>
#include<cmath>
#include<queue>
#include<cstring>
using namespace std;
typedef long long ll;
struct node{
vector<int> zi;
int day;
int ind;
int maxT;
vector<int> last;
int cost;
}sub[500];
vector<int> ans;
int n,c;
void toposort() {
queue<int> q;
for (int i = 1; i <=n; i++)
if (sub[i].ind == 0) q.push(i);
while (!q.empty()) {
int u = q.front();
q.pop();
ans.push_back(u);
for(int i = 0;i<sub[u].last.size ();i++ ){
int cur = sub[u].last[i];
sub[u].maxT = max(sub[cur].cost,sub[u].maxT );
}
sub[u].cost = sub[u].day + sub[u].maxT ;
sub[u].maxT = sub[u].cost ;
for(int i = 0;i<sub[u].zi.size() ;i++ ){
int cur = sub[u].zi[i];
if(--sub[cur].ind == 0 ){
q.push(cur);
}
}
}
return ;
}
int main(){
cin>>n;
for(int i = 1;i<=n;i++){
int t;
cin>>t;
sub[i].day = t;
sub[i].ind = 0;
sub[i].maxT = 0;
sub[i].cost = 0;
}
while(1){
int a,b;cin>>a>>b;
if(a == -1 && b == -1){
break;
}
sub[a].zi.push_back(b);
sub[b].last.push_back(a);
sub[b].ind ++;
}
cin>>c;
toposort();
cout<<sub[c].cost - sub[c].day ;
return 0;
}