bzoj4842 [Neerc2016]Delight for a Cat

传送门：http://www.lydsy.com/JudgeOnline/problem.php?id=4842

【题解】

同 http://www.cnblogs.com/galaxies/p/20170627_c.html

输出一个方案就行了

# include <queue>
# include <stdio.h>
# include <string.h>
# include <iostream>
# include <algorithm>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

const int N = 1e5 + 10, M = 1e5 + 10;
const ll inf = 1e17 + 10;

int n, K, SS, EE;
int s[M], e[M];

int S, T, id[N];
int head[M], nxt[M], to[M], w[M], flow[M], tot = 1;
inline void add(int u, int v, int fl, int _w) {
    ++tot; nxt[tot] = head[u]; head[u] = tot; to[tot] = v;
    flow[tot] = fl, w[tot] = _w;
}
inline void adde(int u, int v, int fl, int _w) {
    add(u, v, fl, _w);
    add(v, u, 0, -_w);
}

namespace MCF {
    queue<int> q;
    int pre[M];
    ll d[M];  bool vis[M];
    inline bool spfa() {
        while(!q.empty()) q.pop();
        for (int i=1; i<=T; ++i) vis[i] = 0, d[i] = inf;
        vis[S] = 1; d[S] = 0; q.push(S);
        while(!q.empty()) {
            int top = q.front(); q.pop(); vis[top] = 0;
            for (int i=head[top]; i; i=nxt[i]) {
                if(d[to[i]] > d[top] + w[i] && flow[i]) {
                    d[to[i]] = d[top] + w[i];
                    pre[to[i]] = i;
                    if(!vis[to[i]]) {
                        vis[to[i]] = 1;
                        q.push(to[i]);
                    }
                }
            }
        }
        return d[T] < inf;
    }
    inline ll mcf() {
        int fl = 1e9; ll ret = 0;
        for (int i=pre[T]; i; i=pre[to[i^1]]) fl = min(fl, flow[i]);
        for (int i=pre[T]; i; i=pre[to[i^1]]) {
            flow[i] -= fl; flow[i^1] += fl;
            ret += 1ll * fl * w[i];
        }
        return ret;
    }
    inline ll main() {
        ll ans = 0;
        while(spfa()) ans += mcf();
        return ans;
    }
}

int main() {
    cin >> n >> K >> SS >> EE;
    ll sum = 0;
    for (int i=1; i<=n; ++i) {
        scanf("%d", &s[i]);
        sum += s[i];
    }
    for (int i=1; i<=n; ++i) {
        scanf("%d", &e[i]);
        e[i] -= s[i];
    }
    int mi = EE, mx = K - SS;
    int S0 = n+1; S = n+2; T = n+3;
    //  [mi, mx] 
    adde(S, S0, mx, 0);
    for (int i=1; i<=n; ++i) {
        if(i <= K) adde(S0, i, 1e9, 0);
        if(i+1 <= n) adde(i, i+1, mx-mi, 0);
        else adde(i, T, mx-mi, 0);
        if(i+K <= n) adde(i, i+K, 1, -e[i]);
        else adde(i, T, 1, -e[i]);
        id[i] = tot;
    }
    cout << sum - MCF::main() << endl;
    for (int i=1; i<=n; ++i) {
        if(flow[id[i]^1]) putchar('S');
        else putchar('E');
    }
    return 0;
}