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This is my 1st 3D DP problem, and it should be an educational one. But, still tricky to me.
Here is a good article: http://www.cnblogs.com/sunshineatnoon/p/3919423.html, and I simply re-code it in C++, for learning :)
#include <cmath> #include <cstdio> #include <vector> #include <map> #include <set> #include <unordered_set> #include <string> #include <climits> #include <iostream> #include <algorithm> #include <unordered_map> #include <unordered_set> using namespace std; int CalcMin(int i, int j, int k, vector<vector<vector<int>>> &dp, vector<string> &map) { int min_mv = INT_MAX - 1; int n = map.size(); int m = map[0].size(); if (i - 1 >= 0) { int newMv = dp[i - 1][j][k - 1] + (map[i - 1][j] == ‘D‘ ? 0 : 1); min_mv = std::min(min_mv, newMv); } if (i + 1 < n) { int newMv = dp[i + 1][j][k - 1] + (map[i + 1][j] == ‘U‘ ? 0 : 1); min_mv = std::min(min_mv, newMv); } if (j - 1 >= 0) { int newMv = dp[i][j - 1][k - 1] + (map[i][j - 1] == ‘R‘ ? 0 : 1); min_mv = std::min(min_mv, newMv); } if (j + 1 < m) { int newMv = dp[i][j + 1][k - 1] + (map[i][j + 1] == ‘L‘ ? 0 : 1); min_mv = std::min(min_mv, newMv); } return min_mv; } int main() { int n, m, K; cin >> n >> m >> K; int sx, sy; vector<string> map; for (int i = 0; i < n; i++) { char buf[60] = { 0 }; scanf("%s", buf); string s(buf); size_t inx; if ((inx = s.find(‘*‘)) != string::npos) { sx = i; sy = inx; } map.push_back(s); } // vector<vector<vector<int>>> dp(n, vector<vector<int>>(m, vector<int>(K + 1))); for (int k = 0; k <= K; k++) for (int i = 0; i < n; i++) for (int j = 0; j < m; j++) { if (k == 0) // INIT { dp[i][j][k] = ((i + j) == 0) ? 0 : INT_MAX - 1; } else { dp[i][j][k] = CalcMin(i, j, k, dp, map); } } // Get Min int ret = INT_MAX - 1; for (int k = 0; k <= K; k++) ret = std::min(ret, dp[sx][sy][k]); cout << (ret == (INT_MAX - 1) ? -1 : ret) << endl; return 0; }
HackerRank - "Coin on the Table" - 3D DP
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原文地址:http://www.cnblogs.com/tonix/p/4506132.html