A. Wallet Exchange
#include<bits/stdc++.h>
using namespace std;
void solve(){
int a,b;
cin>>a>>b;
int k=a+b;
if(!(k&1)){
cout<<"Bob\n";
}else{
cout<<"Alice\n";
}
}
int main(){
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
int t=1;
cin>>t;
for(int i=1;i<=t;i++)solve();
return 0;
}
B. Plus-Minus Split
前缀和
#include<bits/stdc++.h>
using namespace std;
int pre[100000];
void solve(){
int n;
string s;
cin>>n>>s;
for(int i=1;i<=n;i++){
int x;
if(s[i-1]=='-')x=-1;
else x=1;
pre[i]=pre[i-1]+x;
}
cout<<abs(pre[n])<<"\n";
}
int main(){
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
int t=1;
cin>>t;
for(int i=1;i<=t;i++)solve();
return 0;
}
C. Grouping Increases
贪心
#include<bits/stdc++.h>
using namespace std;
const int N=2e5+10;
int a[N];
void solve(){
int n;
cin>>n;
for(int i=1;i<=n;i++){
cin>>a[i];
}
vector<int>s;
vector<int>t;
int ans=0;
s.push_back(a[1]);
for(int i=2;i<=n;i++){
if(t.empty()){
if(s.back()>=a[i]){
s.push_back(a[i]);
}else{
t.push_back(a[i]);
}
}else{
if(s.back()>=a[i]&&t.back()>=a[i]&&s.back()>t.back()){
t.push_back(a[i]);
}else if(s.back()>=a[i]&&t.back()>=a[i]&&s.back()<=t.back()){
s.push_back(a[i]);
}else if(s.back()>=a[i]&&t.back()<a[i]){
s.push_back(a[i]);
}else if(s.back()<a[i]&&t.back()>=a[i]){
t.push_back(a[i]);
}else if(s.back()<a[i]&&t.back()<a[i]){
ans++;
if(t.back()>s.back()){
s.push_back(a[i]);
}else{
t.push_back(a[i]);
}
}
}
}
cout<<ans<<"\n";
}
int main(){
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
int t=1;
cin>>t;
for(int i=1;i<=t;i++)solve();
return 0;
}