poj1163 The Triangle

The Triangle

Time Limit: 1000MS	Memory Limit: 10000K
Total Submissions: 50890	Accepted: 30823

Description

7
3   8
8   1   0
2   7   4   4
4   5   2   6   5

(Figure 1)

Figure 1 shows a number triangle. Write a program that calculates the highest sum of numbers passed on a route that starts at the top and ends somewhere on the base. Each step can go either diagonally down to the left or diagonally down to the right. 

Input

Your program is to read from standard input. The first line contains one integer N: the number of rows in the triangle. The following N lines describe the data of the triangle. The number of rows in the triangle is > 1 but <= 100. The numbers in the triangle, all integers, are between 0 and 99.

Output

Your program is to write to standard output. The highest sum is written as an integer.

Sample Input

5
7
3 8
8 1 0 
2 7 4 4
4 5 2 6 5

Sample Output

30

 

数字三角形。

f[i][j] = max(f[i - 1][j], f[i - 1][j - 1]) + a[i][j]

#include <cstdio>
#include <algorithm>

using namespace std;

int n, f[200][200], ans;

int main() {
  scanf("%d", &n);
  for(int i = 1 ; i <= n ; i ++) {
    for(int j = 1 ; j <= i ; j ++) {
      scanf("%d", &f[i][j]);
      f[i][j] += max(f[i - 1][j], f[i - 1][j - 1]);
      if(i == n) {
        ans = max(ans, f[i][j]);
      }
    }
  }
  printf("%d\n", ans);
}

 

如果要强制经过某一点(x, y)？

a[x][y] += INF

答案再减去INF就行

 

如果禁止进过某一点？

减去INF就行