【矩阵】 HDOJ 5097 Page Rank

#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 20005
#define maxm 4000005
#define eps 1e-10
#define mod 1000000007
#define INF 1e9
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid
#define rson o<<1 | 1, mid+1, R
typedef long long LL;
typedef unsigned long long ULL;
//typedef int LL;
using namespace std;

char g[3005][3005];
double mat[3005][3005];
double res[2][3005];
int n;

void read(void)
{
for(int i = 1; i <= n; i++) scanf("%s", g[i] + 1);
}

bool check(void)
{
double ans = 0;
for(int i = 1; i <= n; i++) ans += (res[0][i] - res[1][i]) * (res[0][i] - res[1][i]);
if(ans < 1e-3) return true;
else return false;
}

void work(void)
{
memset(mat, 0, sizeof mat);
for(int i = 1; i <= n; i++) {
int t = 0;
for(int j = 1; j <= n; j++)
if(g[i][j] == '1') t++;
for(int j = 1; j <= n; j++)
if(g[i][j] == '1') mat[j][i] = 1.0 / t;
}
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
mat[i][j] = 0.85 * mat[i][j] + 0.15 * 1.0 / n;
int now = 0;
for(int i = 1; i <= n; i++) res[now][i] = 1.0;
while(1) {
memset(res[now^1], 0, sizeof res[now^1]);
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
res[now^1][i] += res[now][j] * mat[i][j];
now ^= 1;
if(check()) break;
}
for(int i = 1; i <= n; i++) printf("%.2f%c", res[now][i], i == n ? '\n' : ' ');
}

int main(void)
{
while(scanf("%d", &n)!=EOF) {
read();
work();
}

return 0;
}