UVALive 6508 Permutation Graphs

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Permutation GraphsTime Limit: 3000msMemory Limit: 131072KBThis problem will be judged on UVALive. Original ID: 6508
64-bit integer IO format: %lld      Java class name: Main 解題：逆序數

 1 #include <bits/stdc++.h> 2 using namespace std; 3 typedef long long LL; 4 const int maxn = 100010; 5 int c[maxn],hhash[maxn],n; 6 void add(int i){ 7     while(i > 0){ 8         c[i] += 1; 9         i -= i&-i;10     }11 }12 int sum(int i,int ret = 0){13     while(i < maxn){14         ret += c[i];15         i += i&-i;16     }17     return ret;18 }19 int main(){20     int kase,tmp;21     scanf("%d",&kase);22     while(kase--){23         scanf("%d",&n);24         for(int i = 1; i <= n; ++i){25             scanf("%d",&tmp);26             hhash[tmp] = i;27         }28         memset(c,0,sizeof c);29         LL ret = 0;30         for(int i = 0; i < n; ++i){31             scanf("%d",&tmp);32             ret += sum(hhash[tmp] + 1);33             add(hhash[tmp]);34         }35         printf("%lld\n",ret);36     }37     return 0;38 }

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UVALive 6508 Permutation Graphs