动态规划:
原题链接
这道题的动态转移方程是a[i][j]+=max(a[i-1][j],a[i-1][j-1])
当然,要注意边界问题
#include<iostream>
using namespace std;
int max(int a, int b) {
return a > b ? a : b;
}
int main()
{
int n;
cin >> n;
int a[1001][1001] = { 0 };
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= i; j++) {
cin >> a[i][j];
if (i == 1)
a[i][j] += a[i - 1][j];
else if (j == i)
a[i][j] += a[i - 1][j - 1];
else
a[i][j] += max(a[i - 1][j], a[i - 1][j - 1]);
}
}
int ans = 0;
for (int i = 0; i <= n; i++) {
ans = max(ans, a[n][i]);
}
cout << ans;
return 0;
}
优化一下
#include<iostream>
#include<vector>
#include<climits>
using namespace std;
int max(int a, int b) {
return a > b ? a : b;
}
int main()
{
int n;
cin >> n;
int a[1001] = { 0 };
for (int i = n; i >= 1; i--) {
for (int j = i; j <= n; j++) {
int t;
cin>>t;
a[j]=t+max(a[j+1],a[j]);
}
}
int ans = 0;
for (int i = 1; i <= n; i++) {
ans = max(ans, a[i]);
}
cout << ans;
return 0;
}