### 018429's blog

By 018429, history, 3 years ago,

About the problem 1557B,what's the matter with following code , I can't figure out why it is always failed in case 58 of third test,I am almost crushed @^-^@

#include <bits/stdc++.h>
using namespace std;

int main() {
int t;
cin>>t;
while(t--){
int n,k;
cin >> n >> k;
vector<int> a(n),b(n);
for(int i = 0;i < n;i++){
cin >> a[i];
b[i] = a[i];
}
sort(b.begin(),b.end());
map<int,int> nxt;
for(int i = 0;i < n - 1;i++)nxt[b[i]] = b[i+1];
//nxt[b[n-1]] = b[n-1];
int seg = 1;
for(int i = 1;i < n;i++)if(a[i] != nxt[a[i-1]])seg++;
if(seg <= k){
cout<<"YES"<<endl;
}else{
cout<<"NO"<<endl;
}
}
return 0;
}

Update:


OK,I just rewrite the code,and make a mistake again,when i make nxt[b[n-1] = b[n],I even pass 10th test,then I realize that the last number's next value will be value zero in map when I tempt to access by [].For Example,in the case n = 4,k = 1,arrays like: 3 0 1 2,the code will think this is non-decreasing,Finally,the problem is solved,so happy^_^

• +1