Hdu5088Revenge of Nim II高斯消元

比赛的时候不会写，但是网上有基本一样的题。出题水了。。

这题把每个数拆成2进制，然后就和开关灯一样了。

然后学了下高斯消元

kuangbin大神的高斯消元模板。

http://www.cnblogs.com/kuangbin/archive/2012/09/01/2667044.html

#include<iostream>

#include<cstdio>

#include<cstring>

#include<map>

#include<vector>

#include<stdlib.h>

using namespace std;





typedef long long LL;

LL a[100][1111];



void gao(LL x, LL col)

{

    LL ans = 0;

    while (x){

        a[ans++][col] = x % 2;

        x >>= 1;

    }

}



LL gauss(LL equ, LL var)

{

    LL col; LL k;

    for (col = 0, k = 0; k < equ&&col < var; k++, col++){

        LL kk = k;

        for (LL i = k + 1; i < equ; i++){

            if (a[i][col]>a[kk][col]) kk = i;

        }

        if (kk != k){

            for (LL j = k; j <= var; j++)

                swap(a[k][j], a[kk][j]);

        }

        if (!a[k][col]){

            k--; continue;

        }

        for(int i = k+1;i<equ;i++){

            if(a[i][col]){

                for(int j = col;j<=var;j++){

                    a[i][j]^=a[k][j];

                }

            }

        }

    }

    for(int i = k;i<equ;i++)

        if(a[i][col]) return -1;

    return col - k;

}



int main()

{

    LL T;

    LL n;

    LL vis[1111];



    cin >> T;

    while (T--){

        memset(a,0,sizeof(a));

        cin >> n; LL gg = 0;

        for (LL i = 0; i < n; i++){

            cin >> vis[i]; gg ^= vis[i];

            gao(vis[i], i);

        }

        LL t = gauss(50, n);

        if(t<=0) cout<<"No"<<endl;

        else cout<<"Yes"<<endl;

    }

    return 0;

}