题解

#include <bits/stdc++.h>
using namespace std;
#define V vector
#define all0(x) (x).begin(),(x).end()
#define all1(x) (x).begin()+1,(x).end()
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#define IOS ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
typedef long long LL;
typedef pair<int, int> pi;
typedef pair<LL, LL> pl;
const int N = 35 + 20;
const int INF = 0x3f3f3f3f;
const LL INFLL =0x3f3f3f3f3f3f3f3f;
int a[N][N] , b[N][N];
int dx[] = {-1 , -1};
int dy[] = {0 , -1};
void so() {
		int n ;
		cin >> n;
		for(int i = 1 ; i <= n ; i++){
			for(int j = 1 ; j <= i ; j++ ){
				cin >> b[i][j];
			}
		}
		for(int i = 1; i <= n  ;i++ ){
			for(int j = 1 ; j <= i ; j++){
				for(int k = 0 ; k < 2 ; k++){
					int x = i + dx[k];
					int y = j + dy[k];
					a[i][j] = max(a[i][j] , a[x][y] + b[i][j]);
				}
			}
		}
		
		int ans = 0;
		for(int i = 1; i <= n ; i++){
			ans = max(ans , a[n][i]);
		}
		cout <<ans;
}
int main() {
    IOS
    int tt=1;
  //  cin >> tt;
    while (tt--)
    so();
}