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  1. #include <stdio.h>
  2. #include <math.h>
  3. #include <stdlib.h>
  4. #define ll long long
  5.  
  6. int cmp(const void *a, const void * b){
  7.     int *p1 = (int*)a;
  8.     int *p2 = (int*)b;
  9.     return *p1  - *p2;
  10. }
  11.  
  12.  
  13.  
  14. void solve(){
  15.     int n; scanf("%d", &n);
  16.     int a[n+1];
  17.     for(int i=1; i <=n; i++){
  18.         scanf("%d", a + i);
  19.     }
  20.     int check[n+2] = {0};
  21.     check[a[1]] = 1; //a[i] la vi tri ghe ma khach thu i ngoi; 
  22.     for(int i=2; i <=n; i++){
  23.         if(!check[a[i] + 1] &&  !check[a[i] - 1]){
  24.             printf("NO\n");
  25.             return;
  26.         }
  27.         check[a[i]] = 1; //dat vi tri ghe a[i] = 1 (da co nguoi ngoi)
  28.     }
  29.     printf("YES\n");
  30. }
  31.  
  32. int main(){
  33.     int typetest = 0;
  34.     if(typetest){
  35.         int t; scanf("%d", &t);
  36.         while(t--){
  37.             solve();
  38.         }
  39.     }else solve();
  40. }
Success #stdin #stdout 0s 5268KB
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stdin
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Standard input is empty
stdout
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YES
https://ideone.com/jVA97e
language:
C++14 (gcc 8.3)
created:
5 days ago
visibility:
public

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