Rikka with Nash Equilibrium Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 524288/524288 K (Java/Others) Total Submission(s): 1479 Accepted Submission(s): 599 Problem Description Nash Equilibrium is an important concept in game theory. Rikka and Yuta are playing a simple matrix game. At the beginning of the game, Rikka shows an n×m integer matrix A. And then Yuta needs to choose an integer in [1,n], Rikka needs to choose an integer in [1,m]. Let i be Yuta's number and j be Rikka's number, the final score of the game is Ai,j. In the remaining part of this statement, we use (i,j) to denote the strategy of Yuta and Rikka. For example, when n=m=3 and matrix A is ⎡⎣⎢⎢111241131⎤⎦⎥⎥ If the strategy is (1,2), the score will be 2; if the strategy is (2,2), the score will be 4. A pure strategy Nash equilibrium of this game is a strategy (x,y) which satisfies neither Rikka nor Yuta can make the score higher by changing his(her) strategy unilaterally. Formally, (x,y) is a Nash equilibrium if and only if: {Ax,y≥Ai,y ∀i∈[1,n]Ax,y≥Ax,j ∀j∈[1,m] In the previous example, there are two pure strategy Nash equilibriums: (3,1) and (2,2). To make the game more interesting, Rikka wants to construct a matrix A for this game which satisfies the following conditions: 1. Each integer in [1,nm] occurs exactly once in A. 2. The game has at most one pure strategy Nash equilibriums. Now, Rikka wants you to count the number of matrixes with size n×m which satisfy the conditions. Input The first line contains a single integer t(1≤t≤20), the number of the testcases. The first line of each testcase contains three numbers n,m and K(1≤n,m≤80,1≤K≤109). The input guarantees that there are at most 3 testcases with max(n,m)>50. Output For each testcase, output a single line with a single number: the answer modulo K. Sample Input 2 3 3 100 5 5 2333 Sample Output 64 1170 Source 2018 Multi-University Training Contest 9 Recommend chendu
从大到小填。每次填进去的数都是要在被管住的里面。
#include<iostream> #include<cstdio> #include<string.h> using namespace std; #define ll long long ll dp[81][81][81*81]; ll n,m,mod; ll dfs(ll x,ll y,ll z) { if(dp[x][y][z]!=-1) return dp[x][y][z]; ll temp=0; if(x<n) temp=(temp+(y*(n-x)%mod)*dfs(x+1,y,z+1))%mod; if(y<m) temp=(temp+(x*(m-y)%mod)*dfs(x,y+1,z+1))%mod; if(x*y>z) temp=(temp+(x*y-z)%mod*dfs(x,y,z+1))%mod; return dp[x][y][z]=temp; } int main() { int T; scanf("%d",&T); while(T--) { scanf("%lld%lld%lld",&n,&m,&mod); memset(dp,-1,sizeof dp); dp[n][m][n*m]=1; ll ans=((n*m)%mod*dfs(1,1,1)%mod); printf("%lld ",ans); } return 0; }
找规律看https://www.cnblogs.com/solvit/p/9507207.html