數塔問題，比較基礎。

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;

const int INF=0x3f3f3f3f;
const int maxn=400;
int n;
int a[maxn][maxn];

int main(){
#ifndef ONLINE_JUDGE
    freopen("test.in","r",stdin);
    freopen("test.out","w",stdout);
#endif
    while(~scanf("%d",&n)){
    	memset(a,0,sizeof(a));
    	for(int i=1;i<=n;i++){
    		for(int j=1;j<=i;j++){
    			scanf("%d",&a[i][j]);
    		}
    	}
    	for(int i=n;i>=1;i--){
    		for(int j=1;j<=i;j++){
    			a[i][j]=max(a[i+1][j],a[i+1][j+1])+a[i][j];
    		}
    	}
    	printf("%d\n",a[1][1]);
    }
	return 0;
}