Problem
Equations are given in the format A / B = k, where A and B are variables represented as strings, and k is a real number (floating point number). Given some queries, return the answers. If the answer does not exist, return -1.0.
Example:
Given a / b = 2.0, b / c = 3.0. queries are: a / c = ?, b / a = ?, a / e = ?, a / a = ?, x / x = ? . return [6.0, 0.5, -1.0, 1.0, -1.0 ].
The input is: vector
According to the example above:
equations = [ ["a", "b"], ["b", "c"] ], values = [2.0, 3.0], queries = [ ["a", "c"], ["b", "a"], ["a", "e"], ["a", "a"], ["x", "x"] ].
The input is always valid. You may assume that evaluating the queries will result in no division by zero and there is no contradiction.
Solution - Updated Union Findclass Solution { public double[] calcEquation(String[][] equations, double[] values, String[][] queries) { MapSolution - DFSgraph = new HashMap<>(); Map ratio = new HashMap<>(); double[] res = new double[queries.length]; for (int i = 0; i < equations.length; i++) { String p0 = find(equations[i][0], graph, ratio); String p1 = find(equations[i][1], graph, ratio); graph.put(p0, p1); ratio.put(p0, values[i] * ratio.get(equations[i][1]) / ratio.get(equations[i][0])); } for (int i = 0; i < queries.length; i++) { if (!graph.containsKey(queries[i][0]) || !graph.containsKey(queries[i][1])) { res[i] = -1.0; continue; } String p0 = find(queries[i][0], graph, ratio); String p1 = find(queries[i][1], graph, ratio); if (!p0.equals(p1)) { res[i] = -1.0; continue; } res[i] = ratio.get(queries[i][0]) / ratio.get(queries[i][1]); } return res; } private String find(String str, Map graph, Map ratio) { if (!graph.containsKey(str)) { graph.put(str, str); ratio.put(str, 1.0); return str; } if (graph.get(str).equals(str)) return str; String parent = graph.get(str); String ancestor = find(parent, graph, ratio); graph.put(str, ancestor); ratio.put(str, ratio.get(str)*ratio.get(parent)); return ancestor; } }
class Solution { public double[] calcEquation(String[][] equations, double[] values, String[][] queries) { double[] res = new double[queries.length]; SetSolution - Union Finddict = new HashSet<>(); for (String[] pair: equations) { dict.add(pair[0]); dict.add(pair[1]); } for (int i = 0; i < queries.length; i++) { String[] pair = queries[i]; if (!dict.contains(pair[0]) || !dict.contains(pair[1])) { res[i] = -1.0d; } else { res[i] = dfs(equations, values, pair, new HashSet ()); } } return res; } private double dfs(String[][] equations, double[] values, String[] pair, Set set) { for (int i = 0; i < equations.length; i++) { if (pair[0].equals(equations[i][0]) && pair[1].equals(equations[i][1])) return values[i]; if (pair[0].equals(equations[i][1]) && pair[1].equals(equations[i][0])) return 1.0d/values[i]; } for (int i = 0; i < equations.length; i++) { if (!set.contains(i) && pair[0].equals(equations[i][0])) { set.add(i); double temp = dfs(equations, values, new String[]{equations[i][1], pair[1]}, set)*values[i]; if (temp > 0) return temp; else set.remove(i); } if (!set.contains(i) && pair[0].equals(equations[i][1])) { set.add(i); double temp = dfs(equations, values, new String[]{equations[i][0], pair[1]}, set)/values[i]; if (temp > 0) return temp; else set.remove(i); } } return -1.0d; } }
class Solution { public double[] calcEquation(String[][] equations, double[] values, String[][] queries) { Mapgraph = new HashMap<>(); Map ratio = new HashMap<>(); for (int i = 0; i < equations.length; i++) { union(graph, ratio, equations[i][0], equations[i][1], values[i]); } double[] res = new double[queries.length]; for (int i = 0; i < queries.length; i++) { String s1 = queries[i][0], s2 = queries[i][1]; if (!graph.containsKey(s1) || !graph.containsKey(s2) || !find(graph, ratio, s1).equals(find(graph, ratio, s2))) { res[i] = -1.0d; } else { res[i] = ratio.get(s1)/ratio.get(s2); } } return res; } private void union(Map graph, Map ratio, String s1, String s2, double value) { if (!graph.containsKey(s1)) { graph.put(s1, s1); ratio.put(s1, 1.0d); } if (!graph.containsKey(s2)) { graph.put(s2, s2); ratio.put(s2, 1.0d); } String p1 = find(graph, ratio, s1); String p2 = find(graph, ratio, s2); graph.put(p1, p2); ratio.put(p1, value*ratio.get(s2)/ratio.get(s1)); } private String find(Map graph, Map ratio, String str) { if (str.equals(graph.get(str))) return str; String parent = graph.get(str); String ancestor = find(graph, ratio, parent); graph.put(str, ancestor); ratio.put(str, ratio.get(str)*ratio.get(parent)); return ancestor; } }
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