ZOJ 3735 Josephina and RPG （dp）

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这题应该是动态规划吧，乱猜的。

dp[i][j]表示开始的时候选择第i个人。后来经过战斗&交换变成第j个人。的最优值。

#pragma comment(linker, "/STACK:1024000000,1024000000")#include <cstdio>#include <cmath>#include <cstring>#include <iostream>#include <queue>#include <map>#include <stack>#include <string>#include <algorithm>#include <vector>#include <list>#include <deque>#define LL long long#define DB double#define SI(a) scanf("%d",&a)#define SD(a) scanf("%lf",&a)#define SS(a) scanf("%s",a)#define PF printf#define MM(a,b) memset(a,b,sizeof(a))#define REP(i,a,b) for(int i=a;i<b;i++) #define REPD(i,a,b) for(int i=a;i>b;i--)#define INF 0x3f3f3f3f#define EPS 1e-8#define bug puts("bug")using namespace std;#define N 129DB re[N][N];DB dp[N][N];int n,m;int main(){    #ifndef ONLINE_JUDGE    freopen("in.txt","r",stdin);    #endif    int a;    while(~SI(n)) {        n = n*(n-1)*(n-2)/6;        REP(i,0,n)             REP(j,0,n) SD(re[i][j]);        SI(m);        REP(i,0,n)            REP(j,0,n) dp[i][j] = -1;        REP(i,0,n) dp[i][i] = 1;        while(m--) {            SI(a);            DB tmp = -1;            REP(i,0,n) {                tmp = -1;                REP(j,0,n)                if(dp[i][j]>=0) {                    tmp = max(tmp,dp[i][j]=dp[i][j]*re[j][a]);                }                dp[i][a] = tmp;            }        }        DB ans = -1;        REP(i,0,n) ans = max(ans,dp[i][a]);        PF("%.7lf\n",ans);    }    return 0;}