堆的判断

 1 #include<cstdio>
 2 int n;
 3 long long s[120];
 4 bool pd(int k){
 5     if(k!=1&&s[k]>s[k/2]) return 0;
 6     if(k*2<=n&&!pd(k*2)) return 0;
 7     if(k*2+1<=n&&!pd(k*2+1)) return 0;
 8     return 1;
 9 }
10 int main(){
11     scanf("%d",&n);
12     for(int i=1;i<=n;i++) scanf("%lld",&s[i]);
13     if(pd(1)) printf("Yes\n");
14     else printf("No\n");
15     return 0;
16 }