poj2531 Network Saboteur

来源：互联网发布：风险矩阵法编辑：程序博客网时间：2024/05/16 16:19

做这题算是张见识了，随机化算法，随机啊！！！坑爹呢有木有？

code：

#include <set>#include <map>#include <ctime>#include <queue>#include <cmath>#include <stack>#include <limits>#include <vector>#include <bitset>#include <string>#include <cstdio>#include <cstring>#include <fstream>#include <string.h>#include <iostream>#include <algorithm>#define ls rt<<1#define rs rt<<1|1#define Si set<int>#define LL long long#define pb push_back#define PS printf(" ")#define Vi vector<int>#define LN printf("\n")#define SD(a) scanf("%d",&a)#define PD(a) printf("%d",a)#define SET(a,b) memset(a,b,sizeof(a))#define FF(i,a) for(int i(0);i<(a);i++)#define FD(i,a) for(int i(a);i>=(1);i--)#define FOR(i,a,b) for(int i(a);i<=(b);i++)#define FOD(i,a,b) for(int i(a);i>=(b);i--)#define readf freopen("input.txt","r",stdin)#define writef freopen("output.txt","w",stdout)const int maxn = 21;const int INF = 0x3fffffff;const int BigP = 99991;const int dx[] = {0,1,0,-1};const int dy[] = {1,0,-1,0};const double pi = acos(-1.0);using namespace std;int N,w[maxn][maxn];bool subset[maxn];int main(){    SD(N);    FOR(i,1,N) FOR(j,1,N) SD(w[i][j]);    int sum=0,maxx=0;    int times=100000;    while(times--){        int x=rand()%N+1;        subset[x]=!subset[x];        FOR(i,1,N){            if(subset[i]!=subset[x]) sum+=w[i][x];            if(i!=x && subset[i]==subset[x]) sum-=w[i][x];        }        maxx=max(sum,maxx);    }    PD(maxx);LN;return 0;}