P1216 [USACO1.5][IOI1994]数字三角形 Number Triangles

#include <iostream>
#include <algorithm>
using namespace std;
static int A[1000][1000];
static int dp[1000][1000];
int main(){
  int n;
  int maxi = 0;
  cin>>n;
  for(int i = 0;i < n; i++){
    for(int j = 0;j <= i; j++){
      cin>>A[i][j];
    }
  }
  dp[0][0] = A[0][0];
  for(int i = 1;i < n; i++){
    for(int j = 0;j <= i; j++){
      if(j == 0){
        dp[i][j] = A[i][j] + dp[i-1][j];
      }
      else if(j == i){
        dp[i][j] = A[i][j] + dp[i-1][j-1];
      }
      else dp[i][j] = A[i][j] + max(dp[i-1][j],dp[i-1][j-1]);
      if(maxi < dp[i][j]){
        maxi = dp[i][j];
      }
    }
  }
  cout<<maxi;
}