2527. Fj & haozi

//n:总共楼层数,p起点，m时间，t终点
#include <bits/stdc++.h>
using namespace std;
int n,p,m,t;
int ans = 0;        //方案数 

void dfs(int ind,int time) {
    if(ind > n || time > m) return;
    if(ind == t && time == m) ans++;        //到达终点

    if(ind==n) dfs(ind-1,time+1);
    else if(ind==1) dfs(ind+1,time+1);
    else {
        dfs(ind-1,time+1);
        dfs(ind+1,time+1);
    }
}

int main() {
    int cas;cin>>cas;
    while(cas--) {
        ans = 0;
        cin>>n>>p>>m>>t;
        dfs(p,0);
        cout<<ans<<endl;
    }
    return 0;
} 

#include <iostream>
using namespace std;
int main()
{
    int cas,n,p,m,t;
    cin>>cas;
    for (;cas>0;--cas)
    {
        cin>>n>>p>>m>>t;
        int d[102][102]={0};
        int i,j;
        d[p][0]=1;
        for (j=1;j<m+1;++j)
            for (i=1;i<n+1;++i)
                d[i][j]=d[i-1][j-1]+d[i+1][j-1];
        cout<<d[t][m]<<endl;
    }
}

//dp[i][j]表示第i分钟到第j栋房子的方案
#include <iostream>
#include <string.h>
using namespace std;

const int maxn = 101;
int dp[maxn][maxn];
int n;
int m;
int _begin;
int _end;


int main() {
    int num;
    cin >> num;
    for (int k = 0; k < num; ++k) {
        memset(dp, 0, sizeof(dp));
        cin >> n >> _begin >> m >> _end;
        dp[0][_begin] = 1;
        for (int i = 1; i <= m; ++i) {
            for (int j = 1; j <= n; ++j) {
                if (j < n) {
                    dp[i][j] = dp[i - 1][j - 1] + dp[i - 1][j + 1];
                }
                else {
                    dp[i][j] = dp[i - 1][j - 1];
                }
            }
        }
        cout << dp[m][_end] << endl;
    }
    return 0;
}

#include <iostream>
using namespace std;

int n;
int m;
int _begin;
int _end;
int ans;

void DFS(int index, int count) {
    if (count == m) {
        if (index == _end) {
            ans++;
        }
        return;
    }
    if (index < n) {
        DFS(index + 1, count + 1);
    }
    if (index > 1) {
        DFS(index - 1, count + 1);
    }
}

int main() {
    int num;
    cin >> num;
    for (int i = 0; i < num; ++i) {
        cin >> n >> _begin >> m >> _end;
        ans = 0;
        DFS(_begin, 0);
        cout << ans << endl;
    }
    return 0;
}