codechef Sums in a Triangle题解

Let's consider a triangle of numbers in which a number appears in the first line, two numbers appear in the second line, three in the third line, etc. Develop a program which will compute the largest of the sums of numbers that appear on the paths starting from the top towards the base, so that:

• on each path the next number is located on the row below, more precisely either directly below or below and one place to the right;
• the number of rows is strictly positive, but less than 100
• all numbers are positive integers between O and 99.

Input

In the first line integer n - the number of test cases (equal to about 1000).
Then n test cases follow. Each test case starts with the number of lines which is followed by their content.

Output

For each test case write the determined value in a separate line.

Example

Input:2312 11 2 34 1 1 2 4 1 22 3 1 1 Output:59

使用动态规划法解决本题。

和一题leetcode题一样，从底往上查找路径。

#include <vector>#include <string>#include <algorithm>#include <stdio.h>#include <iostream>using namespace std;int triPath(vector<vector<int> > &tri){if (tri.empty()) return 0;vector<int> path(tri.back());for (int i = (int)tri.size() - 2; i >= 0 ; i--)//unsigned做减法会溢出！！！{for (int j = 0; j < (int)tri[i].size(); j++){path[j] = max(path[j], path[j+1]) + tri[i][j];}}return path.front();}int SumsinATriangle(){int T, n;scanf("%d", &T);while (T--){scanf("%d", &n);vector<vector<int> > tri;for (int i = 1; i <= n; i++){vector<int> tmp(i);for (int j = 0; j < i; j++){scanf("%d", &tmp[j]);}tri.push_back(tmp);}printf("%d\n", triPath(tri));}return 0;}