HDU 2151(Worm)

設置好狀態之後轉移就簡單了，狀態轉移方程

 dp[i][j] = dp[i - 1][j - 1] + dp[i - 1][j + 1]，i表示第i分鐘，j表示在第幾棵樹

#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;

const int N = 110;
int dp[N][N];//times, postion

int main(){
	int n, p, m, t;
	while(cin >> n >> p >> m >> t){
		int i, j;
		memset(dp, 0, sizeof(dp));
		dp[0][p] = 1;
		for(i = 1;i <= m;i++)
			for(j = 1;j <= n;j++)
				dp[i][j] = dp[i - 1][j - 1] + dp[i - 1][j + 1];
		cout << dp[m][t] << endl;
	}
	return 0;
}