POJ 1007

 题意：逆序对

 

总结：我私下里WA了好几次，才发现我从前的逆序对写法是有错误的。要注意统计逆序对时加的数量

 

统计：2WA, 1CE

 

 

#include <iostream>#include <algorithm>#include <string>#include <cstring>#define FOR(i,a,b) for (int i=a;i<=b;i++)using namespace std;class node{public:int v,o;string s;node(){}bool operator <(const node& b) const{if (v!=b.v)return (v<b.v);return (o<b.o);}friend ostream& operator << (ostream& os,const node& b){os << b.s;return os;}};node a[101];string str;char c[101];int mergesort(int l, int r){int ret=0;if (l<r){int mid=(l+r)/2;int a=mergesort(l, mid);int b=mergesort(mid+1, r);ret=a+b;int i=l, j=mid+1;int total=l;while(i<=mid || j<=r){if (j>r || (i<=mid && str[i]<=str[j]) )c[total++]=str[i++];else{c[total++]=str[j++];ret+=mid-i+1;}}FOR(i,l,r)str[i]=c[i];}//cout << l << "," << r << " " << ret << " " << str<< endl;return ret;}int n, len;int main(){//freopen ("in.txt","r",stdin);//freopen ("out.txt","w",stdout);len=0;n=0;cin >> len >> n;FOR(i,1,n){cin >> str;a[i].s=str;a[i].o=i;a[i].v=mergesort(0, len-1);}sort(&a[1], &a[n+1]);FOR(i,1,n)cout << a[i] << endl;return 0;}