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  • 星际转移问题

    S向地球连k的边,每天每个地方由上一天连INF边,每天月亮向T连边
    枚举天数获取每天飞船的位置,由上一天的位置向这一天连满载的边
    跑到人都送完位置,在合适的时候(玄学)break输出无解

    # include <stdio.h>
    # include <stdlib.h>
    # include <iostream>
    # include <string.h>
    # include <math.h>
    # define ll long long
    # define RG register
    # define IL inline
    # define Mem(a, b) memset(a, b, sizeof(a))
    # define Max(a, b) (((a) > (b)) ? (a) : (b))
    # define Min(a, b) (((a) < (b)) ? (a) : (b))
    using namespace std;
    
    IL int Get(){
        RG char c = '!'; RG int x = 0, z = 1;
        for(; c > '9' || c < '0'; c = getchar()) z = (c == '-') ? -1 : 1;
        for(; c >= '0' && c <= '9'; c = getchar()) x = x * 10 + c - '0';
        return x * z;
    }
    
    const int INF = 2147483647, MAXN = 50001, MAXM = 2000001;
    int r[MAXN], h[MAXN], n, m, ft[MAXN], cnt, ans, map[31][31], Q[MAXM], level[MAXN], cur[MAXN], k;
    struct Edge{
        int to, nt, f;
    } edge[MAXM];
    
    IL void Add(RG int u, RG int v, RG int f){
        edge[cnt] = (Edge){v, ft[u], f}; ft[u] = cnt++;
        edge[cnt] = (Edge){u, ft[v], 0}; ft[v] = cnt++;
    }
    
    IL int Dfs(RG int u, RG int T, RG int maxf){
        if(u == T) return maxf;
        RG int ret = 0;
        for(RG int &e = cur[u]; e != -1; e = edge[e].nt){
            RG int v = edge[e].to;
            if(level[v] == level[u] + 1 && edge[e].f){
                RG int f = Dfs(v, T, Min(maxf - ret, edge[e].f));
                edge[e].f -= f; edge[e ^ 1].f += f;
                ret += f;
                if(ret == maxf) break;
            }
        }
        return ret;
    }
    
    IL bool Bfs(RG int S, RG int T){
        Mem(level, 0);
        RG int head = 0, tail = 0;
        Q[0] = S; level[S] = 1;
        while(head <= tail){
            RG int u = Q[head++];
            if(u == T) return 1;
            for(RG int e = ft[u]; e != -1; e = edge[e].nt){
                RG int v = edge[e].to;
                if(!level[v] && edge[e].f){
                    level[v] = level[u] + 1;
                    Q[++tail] = v;
                }
            }
        }
        return 0;
    }
    
    int main(){
        Mem(ft, -1);
        n = Get(); m = Get(); k = Get();
        RG int S = 0, T = 50000;
        for(RG int i = 1; i <= m; i++){
            h[i] = Get(); r[i] = Get();
            for(RG int j = 1; j <= r[i]; j++)
                map[i][j] = Get(), map[i][j] += 2;
        }
        Add(S, 2, k);
        for(RG int i = 1; i <= (k + 2) * (n + 2); i++){
            //枚举天
            RG int t1 = (i - 1) * (n + 2), t2 = i * (n + 2);
            for(RG int j = 1; j <= m; j++){
                RG int u = t1 + map[j][(i - 1) % r[j] + 1], v = t2 + map[j][i % r[j] + 1];
                Add(u, v, h[j]);
                //当前位置 
            }
            for(RG int j = 1; j <= n + 2; j++)
                Add(t1 + j, t2 + j, INF);
            //昨天向今天
            Add(t2 + 1, T, INF);
            //每天月亮
            while(Bfs(S, T)){
                for(RG int j = S; j <= T; j++)
                    cur[j] = ft[j];
                ans += Dfs(S, T, INF);
            }
            if(ans >= k) return !printf("%d
    ", i);
        }
        printf("0
    ");
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/cjoieryl/p/8206328.html
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