solve.cpp

#include <stdio.h>
#include <stdlib.h>
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
class Solution {
	public:
		int minPathSum(vector<vector<int>> &grid) {
			return minPathSum1(grid);
		}
	private:
		int minPathSum1(vector<vector<int>> &grid) {
			if (grid.size() < 1)
				return 0;
			int n = grid.size();
			int m = grid[0].size();
			vector<vector<int>> dp(n, vector<int>(m, 0));
			dp[0][0] = grid[0][0];
			for (int i = 1; i < n; ++i)
				dp[i][0] = dp[i - 1][0] + grid[i][0];
			for (int j = 1; j < m; ++j)
				dp[0][j] = dp[0][j - 1] + grid[0][j];
			for (int i = 1; i < n; ++i)
				for (int j = 1; j < m; ++j)
					dp[i][j] = min(dp[i - 1][j], dp[i][j - 1]) + grid[i][j];
			return dp[n - 1][m - 1];
		}
		int minPathSum2(vector<vector<int>> &grid) {
			if (grid.size() < 1)
				return 0;
			int n = grid.size();
			int m = grid[0].size();
			vector<int> dp(n, 0);
			dp[0] = grid[0][0];
			for (int i = 1; i < n; ++i)
				dp[i] = dp[i - 1] + grid[i][0];
			for (int i = 1; i < n; ++i)
				for (int j = 1; j < n; ++j) {
					dp[j] = min(dp[j], dp[j - 1]) + grid[i][j];
				}
			return dp[n - 1];
		}
};
int main(int argc, char **argv)
{
	Solution solution;
	int n, m;
	while (scanf("%d%d", &n, &m) != EOF) {
		vector<vector<int>> v(n, vector<int>(m, 0));
		for (int i = 0; i < n; ++i)
			for (int j = 0; j < m; ++j) {
				cin >> v[i][j];
			}
		cout << solution.minPathSum(v) << endl;
	}
	return 0;
}