• #6030. 「雅礼集训 2017 Day1」矩阵 [贪心]


    无解肯定是一个都没有。
    首先你要想到一个贪心策略
    就是要染满一列,然后再染其他列
    很显然可以用 (k) 行染 (k) 列,然后你发现,如果第 (k) 列没有?
    随便挑个来染上,多1的代价。
    最后的话,看一下有多少个没染完的,搞下就完了

    只能scanf,wdnmd

    // powered by c++11
    // by Isaunoya
    #include <bits/stdc++.h>
    #define rep(i, x, y) for (register int i = (x); i <= (y); ++i)
    #define Rep(i, x, y) for (register int i = (x); i >= (y); --i)
    using namespace std;
    using db = double;
    using ll = long long;
    using uint = unsigned int;
    #define Tp template
    using pii = pair<int, int>;
    #define fir first
    #define sec second
    Tp<class T> void cmax(T& x, const T& y) {
        if (x < y)
            x = y;
    }
    Tp<class T> void cmin(T& x, const T& y) {
        if (x > y)
            x = y;
    }
    #define all(v) v.begin(), v.end()
    #define sz(v) ((int)v.size())
    #define pb emplace_back
    Tp<class T> void sort(vector<T>& v) { sort(all(v)); }
    Tp<class T> void reverse(vector<T>& v) { reverse(all(v)); }
    Tp<class T> void unique(vector<T>& v) { sort(all(v)), v.erase(unique(all(v)), v.end()); }
    const int SZ = 1 << 23 | 233;
    struct FILEIN {
        char qwq[SZ], *S = qwq, *T = qwq, ch;
    #ifdef __WIN64
    #define GETC getchar
    #else
        char GETC() { return (S == T) && (T = (S = qwq) + fread(qwq, 1, SZ, stdin), S == T) ? EOF : *S++; }
    #endif
        FILEIN& operator>>(char& c) {
            while (isspace(c = GETC()))
                ;
            return *this;
        }
        FILEIN& operator>>(string& s) {
            while (isspace(ch = GETC()))
                ;
            s = ch;
            while (!isspace(ch = GETC())) s += ch;
            return *this;
        }
        Tp<class T> void read(T& x) {
            bool sign = 0;
            while ((ch = GETC()) < 48) sign ^= (ch == 45);
            x = (ch ^ 48);
            while ((ch = GETC()) > 47) x = (x << 1) + (x << 3) + (ch ^ 48);
            x = sign ? -x : x;
        }
        FILEIN& operator>>(int& x) { return read(x), *this; }
        FILEIN& operator>>(ll& x) { return read(x), *this; }
    } in;
    struct FILEOUT {
        const static int LIMIT = 1 << 22;
        char quq[SZ], ST[233];
        int sz, O;
        ~FILEOUT() { flush(); }
        void flush() {
            fwrite(quq, 1, O, stdout);
            fflush(stdout);
            O = 0;
        }
        FILEOUT& operator<<(char c) { return quq[O++] = c, *this; }
        FILEOUT& operator<<(string str) {
            if (O > LIMIT)
                flush();
            for (char c : str) quq[O++] = c;
            return *this;
        }
        Tp<class T> void write(T x) {
            if (O > LIMIT)
                flush();
            if (x < 0) {
                quq[O++] = 45;
                x = -x;
            }
            do {
                ST[++sz] = x % 10 ^ 48;
                x /= 10;
            } while (x);
            while (sz) quq[O++] = ST[sz--];
        }
        FILEOUT& operator<<(int x) { return write(x), *this; }
        FILEOUT& operator<<(ll x) { return write(x), *this; }
    } out;
    #define int long long
    
    const int maxn = 1e3 + 31;
    char a[maxn][maxn];
    signed main() {
        // code begin.
        int n;
        scanf("%lld", &n);
        bool v = 0;
        vector<int> cntx(n + 3, 0), cnty(n + 3, 0);
        rep(i, 1, n) {
            scanf("%s", a[i] + 1);
            rep(j, 1, n) {
                if (a[i][j] == '#') {
                    v = 1;
                    ++cntx[i], ++cnty[j];
                }
            }
        }
        if (!v)
            out << -1 << '
    ';
        else {
            int ans = n;
            rep(i, 1, n) if (cnty[i]) cmin(ans, n - cntx[i]);
            else cmin(ans, n - cntx[i] + 1);
            rep(i, 1, n) if (cnty[i] != n)++ ans;
            out << ans << '
    ';
        }
        return 0;
        // code end.
    }
    
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  • 原文地址:https://www.cnblogs.com/Isaunoya/p/12397059.html
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