HDU 1487高斯消元

這題，狀態建立不難，坑比較多，一個是可能數字多位，還可能出現負數，還有可能個別元素不能求出期望，但是其他某些元素可以求出期望，着讓我一直wa，直到最後，取消row–才ac，真坑。

//
//  Created by Running Photon on 2016-03-16
//  Copyright (c) 2015 Running Photon. All rights reserved.
//
#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <string>
#include <sstream>
#include <set>
#include <vector>
#include <stack>
#define ALL(x) x.begin(), x.end()
#define INS(x) inserter(x, x,begin())
#define ll long long
#define CLR(x) memset(x, 0, sizeof x)
using namespace std;
const double inf = 10000000000;
const int MOD = 1e9 + 7;
const int maxn = 1e4 + 10;
const int maxv = 5e2 + 10;
const double eps = 1e-5;

char s[maxv][maxv];
double A[maxv][maxv];
double e[maxv];
int n;
int vis[maxv];
int Free[maxv];
void dfs(int row, int col) {
    int len = strlen(s[row]);
    int cnt = 0;
    CLR(e);
    vis[0] = 4;
    for(int i = col; i < len - 1; i++) {
        if(s[row][i] == '(') {
            e[vis[cnt]] += 1;
            vis[++cnt] = i;
        }
        if(s[row][i] == ')') {
            cnt--;
        }
        if(isdigit(s[row][i]) || s[row][i] == '-') {
            e[vis[cnt]] += 1;
            while(isdigit(s[row][i]) || s[row][i] == '-') {
                i++;
            }
            i--;
        }
        if(isalpha(s[row][i])) e[vis[cnt]] += 1;
    }
}
void debug(int edu, int var) {
    for(int i = 0; i < edu; i++) {
        for(int j = 0; j <= var; j++) {
            printf("%f   ", A[i][j]);
        }
        puts("");
    }
    puts("");
}
double res[maxv];
void Guass(int edu, int var) {
    int col, row;
    CLR(Free);
    for(col = 0, row = 0; row < edu && col < var; col++, row++) {
        int max_row = row;
        for(int i = row + 1; i < edu; i++) {
            if(abs(A[i][col]) > abs(A[max_row][col])) {
                max_row = i;
            }
        }
        if(max_row != row) {
            for(int j = 0; j <= var; j++) {
                swap(A[max_row][j], A[row][j]);
            }
        }
        if(abs(A[row][col]) < eps) {
//            row--;
            Free[col] = 1;
            continue;
        }
        for(int i = row + 1; i < edu; i++) {
            if(abs(A[i][col]) < eps) continue;
            double k = A[i][col] / A[row][col];
            A[i][col] = 0;
            for(int j = col + 1; j <= var; j++) {
                A[i][j] -= A[row][j] * k;
            }
        }
    }
    debug(edu, var);
    for(int i = var - 1; i >= 0; i--) {
        if(abs(A[i][i]) < eps) {Free[i] = 1; continue;}
        res[i] = A[i][var];
        for(int j = var - 1; j > i; j--) {
            if(Free[j] && abs(A[i][j]) > eps) {Free[i] = 1; break;}
            res[i] -= res[j] * A[i][j];
        }
        res[i] /= A[i][i];
    }
}
int main() {
#ifdef LOCAL
    freopen("in.txt", "r", stdin);
//  freopen("out.txt","w",stdout);
#endif
//  ios_base::sync_with_stdio(0);
    int cas = 0;
    while(scanf("%d\n", &n) != EOF && n) {
        printf("Game %d\n", ++cas);
        for(int i = 0; i < n; i++) {
            gets(s[i]);
//            for(int k = 0; k < 4; k++)
//                s[i].erase(s[i].begin());
//            cout << s[i] << endl;
        }
        CLR(A); CLR(e); CLR(res);
        for(int i = 0; i < n; i++) A[i][i] = 1;
        for(int i = 0; i < n; i++) {
            vis[0] = 0;
            dfs(i, 5);
            stack <double> sta;
            sta.push(1 / e[4]);
            double tmp = 1 / e[4];
            int len = strlen(s[i]);
            for(int j = 5; j < len; j++) {
                double x = 0;
                int f = 1;
                if(s[i][j] == '-') {
                    f = -1;
                    j++;
                }
                if(isdigit(s[i][j])) {
                    while(isdigit(s[i][j])) {
                        x = x * 10 + s[i][j] - '0';
                        j++;
                    }
                    j--;
                    A[i][n] += tmp * x * f;
                }
                if(isalpha(s[i][j])) {
                    int y = s[i][j] - 'a';
                    A[i][y] -= tmp;
                }
                if(s[i][j] == '(') {
                    tmp *= 1 / e[j];
                    sta.push(1 / e[j]);
                }
                if(s[i][j] == ')') {
                    tmp /= sta.top();
                    sta.pop();
                }
            }
        }
        Guass(n, n);
        for(int i = 0; i < n; i++) {
            if(!Free[i]) printf("Expected score for %c = %.3f\n", i + 'a', res[i]);
            else printf("Expected score for %c undefined\n", i + 'a');
        }
        puts("");
    }
    return 0;
}