A - Not Overflow
Question meaning: judge whether an input number is between the 31st power of - 2 and the 31st power of - 1
Idea: note that the input range is actually to input a long long number and find out whether an input number is in the int range.
Simple questions can be judged directly
#include<bits/stdc++.h> using namespace std; int main() { long long ans=0; cin>>ans; if(ans>=(-1)*quickpow(2,31)&&ans<=quickpow(2,31)-1) { scYes; } else { scNo; } return 0; }
B - Matrix Transposition
Input a matrix and output the inverse of the matrix.
Idea: at first, I wanted to do it directly. I used to use array to simulate, but I found that the boundary would reach 1e5, and the classic opening was not enough, so I used vector array to simulate the output backwards.
#include<bits/stds++.h> using namespace std; const int maxn=1e5+100; vector<int >a[maxn]; int main() { int n,i,j,m; cin>>n>>m; for(i=0;i<n;i++) { for(j=0;j<m;j++) { int d1; cin>>d1; a[i].push_back(d1); } } for(i=0;i<m;i++) { for(j=0;j<n;j++) { cout<<a[j][i]<<" "; } cout<<endl; } return 0; }
C - kasaka
Question meaning: if you enter a string, you can only add a from the front to find out whether it is a complete palindrome string after adding.
Idea: at the beginning, I didn't see the scope clearly. I wanted to delete the character a from the front and back respectively, and then delete it through the position of the marking machine. I don't know what's wrong with this idea. I kept wa. After careful consideration, I found that it still needs to judge the two situations of ba and ab, and then it passed. In fact, it is judged that the number of broken leading a is greater than the current leading a, which is still too small.
#include<bits/stdc++.h> using namespace std; int main() { string s1,s2; int flag1=0,flag2=0; cin>>s1; for(int i=0;i<s1.length()/2;i++) { if(s1[i]!=s1[s1.length()-i-1]) { flag1=1; } } if(flag1==0) { scYes } else { int d1=s1.length(); int d2=s1.length()/2; int i,f1=s1.length(),f2=0; int cnt1=0,cnt2=0; for(i=d1-1;i>0;i--) { if(s1[i]=='a') {cnt1++;continue;} else break; } f2=i; for(i=0;i<d1;i++) { if(s1[i]=='a') {cnt2++;continue;} else break; } f1=i; if(cnt2>=cnt1) { scNo; return 0; } for(int i=f1;i<=f2;i++) { s2+=s1[i]; } int ff=0; for(int i=0;i<s2.length()/2;i++) { if(s2[i]!=s2[s2.length()-i-1]) { ff=1; } } if(ff==0) { scYes } else { scNo; } } return 0; }
D - LR insertion
Give you n+1 numbers, and then follow the requirements of the string it gives. For example, if you give you a string that is
"LR", then the first step is to add a 1 to the left of 0, and then add a 2 from the right of 1, so the final result is 120
Idea: at first, I wanted to do it with data structures such as queues and stacks. It seemed that they couldn't solve this problem. Then I forgot about the linked list. As a result, I found that they actually said it was a double ended queue??? WTF, after thinking for a long time, I found it impossible. As a result, the first step of looking at other people's code reverses the string, so here we need a reverse idea. If you reverse all operations, you will find that this is a naked double ended queue, but I still didn't find out how they came up with it...
#include<bits/stdc++.h> using namespace std; int main() { int n,i,j,t; string s1; deque<int >d1; cin>>n>>s1; reverse(s1.begin(),s1.end()); d1.push_back(n); n-=1; for(i=0;i<s1.length();i++) { if(s1[i]=='L') { d1.push_front(n); } else { d1.push_back(n); } n-=1; } int length=d1.size(); reverse(d1.begin(),d1.end()); for(i=0;i<length;i++) { cout<<d1.front()<<" "; d1.pop_front(); } return 0; }