SumTri_XI

#include <bits/stdc++.h>

using namespace std;
ifstream fin("sumtri_xi.in");
ofstream fout("sumtri_xi.out");
long long n;
vector <vector <long long>> A, DP;

int main()
{
    long long i, j;
    fin>>n;
    A=DP=vector <vector <long long>> (n + 1, vector <long long> (n + 1, 0));
    for(i=1; i<=n; i++)
        for(j=1; j<=i; j++)
            fin>>A[i][j];
    for(j=1; j<=n; ++ j)
        for(i=j; i<=n; ++ i)
        	DP[i][j]=A[i][j]+max(DP[i - 1][j - 1], DP[i][j - 1]);
    fout << DP[n][n];
    return 0;
}