外星千足虫(Alien Millipede) 题解

思路分析

按题目要求使用对应数据结构与算法模拟/递推求解，注意数据范围边界与时间复杂度。

参考代码

#include <algorithm>
#include <bitset>
#include <iostream>
#include <string>
#include <vector>
using namespace std;

const int MAXN = 1005;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    if (!(cin >> n >> m)) return 0;
    vector<bitset<MAXN>> mat(m);
    for (int i = 0; i < m; ++i) {
        string s;
        int b;
        cin >> s >> b;
        for (int j = 0; j < n; ++j) {
            if (s[j] == '1') mat[i].set(j);
        }
        if (b) mat[i].set(n);
    }

    int max_row_used = 0;
    for (int col = 0; col < n; ++col) {
        int piv = -1;
        for (int i = col; i < m; ++i) {
            if (mat[i].test(col)) {
                piv = i;
                break;
            }
        }
        if (piv == -1) {
            cout << "Cannot Determine\n";
            return 0;
        }
        max_row_used = max(max_row_used, piv + 1);
        swap(mat[col], mat[piv]);
        for (int i = 0; i < m; ++i) {
            if (i != col && mat[i].test(col)) {
                mat[i] ^= mat[col];
            }
        }
    }

    cout << max_row_used << "\n";
    for (int i = 0; i < n; ++i) {
        cout << (mat[i].test(n) ? "?y7M#\n" : "Earth\n");
    }
    return 0;
}