【水题】 Codeforces Round #289 509A Maximum in Table

题意：

a[i][j]=a[i-1][j]+a[i][j-1];

#include <cstdio>#include <cstring>#include <cstdlib>#include <string>#include <iostream>#include <algorithm>#include <sstream>#include <cmath>using namespace std;#include <queue>#include <stack>#include <set>#include <vector>#include <deque>#include <map>#define cler(arr, val)    memset(arr, val, sizeof(arr))typedef long long  LL;const int MAXN = 120000;const int MAXM = 140000;const int INF = 0x3f3f3f3f;const int mod = 1000000007;#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1int main(){    int n,a[22][22];    cin>>n;    for(int i=1;i<=n;i++)        a[1][i]=a[i][1]=1;    for(int i=2;i<=n;i++)        for(int j=2;j<=n;j++)            a[i][j]=a[i-1][j]+a[i][j-1];    cout<<a[n][n]<<endl;}