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• import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.HashMap;
  import java.util.Map.Entry;
  
  
  /*
  
  Suppose Andy and Doris want to choose a restaurant for dinner, and they both have a list of favorite restaurants represented by strings.
  
  You need to help them find out their common interest with the least list index sum. If there is a choice tie between answers, output all of them with no order requirement. You could assume there always exists an answer.
  
  Example 1:
  Input:
  ["Shogun", "Tapioca Express", "Burger King", "KFC"]
  ["Piatti", "The Grill at Torrey Pines", "Hungry Hunter Steakhouse", "Shogun"]
  
  Output: ["Shogun"]
  
  Explanation: The only restaurant they both like is "Shogun".
  
  Example 2:
  Input:
  ["Shogun", "Tapioca Express", "Burger King", "KFC"]
  ["KFC", "Shogun", "Burger King"]
  
  Output: ["Shogun"]
  
  Explanation: The restaurant they both like and have the least index sum is "Shogun" with index sum 1 (0+1).
  
  
  Note:
  The length of both lists will be in the range of [1, 1000].
  The length of strings in both lists will be in the range of [1, 30].
  The index is starting from 0 to the list length minus 1.
  No duplicates in both lists.
  
  
   */
  
  public class Minimum_Index_Sum_of_Two_Lists {
  
  	public static void main(String[] args) {
  		Minimum_Index_Sum_of_Two_Lists out = new Minimum_Index_Sum_of_Two_Lists();
  		Solution s = out.new Solution();
  
  		String[] s1 = new String[]{"Shogun","Tapioca Express","Burger King","KFC"};
  		String[] s2 = new String[]{"KFC","Burger King","Tapioca Express","Shogun"};
  		System.out.println(Arrays.toString(s.findRestaurant(s1, s2)));
  
  		Solution2 sl2 = out.new Solution2();
  
  		String[] s21 = new String[]{"Shogun","Tapioca Express","Burger King","KFC"};
  		String[] s22 = new String[]{"KFC","Burger King","Tapioca Express","Shogun"};
  		System.out.println(Arrays.toString(sl2.findRestaurant(s21, s22)));
  	}
  
      // o(n^2)
  	public class Solution {
  	    public String[] findRestaurant(String[] list1, String[] list2) {
  	        if (list1 == null || list2 == null || list1.length == 0 || list2.length == 0) {
  	            return new String[]{""};
  	        }
  
  	        // maintain 2 indexes, both pointing to the same restaurant
  	        int index1 = -1; // minus: not-found
  	        int index2 = -1;
  	        int min = Integer.MAX_VALUE;
  	        ArrayList<String> restaurant = new ArrayList<String>(30); // length of strings 1-30
  
  	        for (int i = 0; i < list1.length; i++) {
  	            for (int j = 0; j < list2.length; j++) {
  	                if (list1[i].equals(list2[j]) && (i + j < min)) {
  	                    // record indexes
  	                    min = i + j;
  	                    restaurant = new ArrayList<String>(30);
  	                    restaurant.add(list1[i]);
  	                } else if (list1[i].equals(list2[j]) && (i + j == min)) {
  	                    // choice tie, then print all of them
  	                    restaurant.add(list1[i]);
  	                }
  	            }
  	        }
  
  	        return restaurant.toArray(new String[restaurant.size()]);
  
  	        // @note: below has runtime error: java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.String;
  	        //return (String[]) restaurant.toArray();
  	    }
  	}
  
  	// o(m+n), extra space
  	public class Solution2 {
  	    public String[] findRestaurant(String[] list1, String[] list2) {
  	        if (list1 == null || list2 == null || list1.length == 0 || list2.length == 0) {
  	            return new String[]{""};
  	        }
  
  	        // maintain 2 indexes, both pointing to the same restaurant
  	        int index1 = -1; // minus: not-found
  	        int index2 = -1;
  	        int min = Integer.MAX_VALUE;
  	        ArrayList<String> restaurant = new ArrayList<String>(30); // length of strings 1-30
  
  	        // @note: use 2 hashmap: 1.store name => index, 2.store sumIndex => word
  
  	        // store list1 for o(1) access
  	        HashMap<String, Integer> hmList1 = new HashMap<>();
  	        for (int i = 0; i < list1.length; i++) {
  	            hmList1.put(list1[i], i);
  	        }
  
  	        // store sumIndex => word
  	        int minIndex = Integer.MAX_VALUE;
  	        for (int j = 0; j < list2.length; j++) {
  	            if (hmList1.containsKey(list2[j])) {
  	                // common interest
  	                int sum = j + hmList1.get(list2[j]);
  		            if (sum < minIndex) {
  		            	minIndex = sum; // update minIndex
  
  		            	restaurant = new ArrayList<String>(30);
  		            	restaurant.add(list2[j]);
  		            } else if (sum == minIndex) {
  		            	restaurant.add(list2[j]);
  		            }
  	            }
  	        }
  
  	        return restaurant.toArray(new String[restaurant.size()]);
  	    }
  	}
  }
  
  ############
  
  class Solution {
      public String[] findRestaurant(String[] list1, String[] list2) {
          Map<String, Integer> mp = new HashMap<>();
          for (int i = 0; i < list2.length; ++i) {
              mp.put(list2[i], i);
          }
          List<String> ans = new ArrayList<>();
          int mi = 2000;
          for (int i = 0; i < list1.length; ++i) {
              if (mp.containsKey(list1[i])) {
                  int t = i + mp.get(list1[i]);
                  if (t < mi) {
                      ans = new ArrayList<>();
                      ans.add(list1[i]);
                      mi = t;
                  } else if (t == mi) {
                      ans.add(list1[i]);
                  }
              }
          }
          return ans.toArray(new String[0]);
      }
  }
  

• // OJ: https://leetcode.com/problems/minimum-index-sum-of-two-lists/
  // Time: O(L1 + L2)
  // Space: O(L1)
  class Solution {
  public:
      vector<string> findRestaurant(vector<string>& list1, vector<string>& list2) {
          unordered_map<string, int> m;
          for (int i = 0; i < list1.size(); ++i) m[list1[i]] = i;
          int minSum = INT_MAX;
          vector<string> ans;
          for (int i = 0; i < list2.size() && i <= minSum; ++i) {
              if (m.find(list2[i]) == m.end() || i + m[list2[i]] > minSum) continue;
              if (i + m[list2[i]] < minSum) {
                  ans.clear();
                  minSum = i + m[list2[i]];
              }
              ans.push_back(list2[i]);
          }
          return ans;
      }
  };
  

• class Solution:
      def findRestaurant(self, list1: List[str], list2: List[str]) -> List[str]:
          ans = []
          mp = {v: i for i, v in enumerate(list2)}
          mi = 2000
          for i, v in enumerate(list1):
              if v in mp:
                  t = i + mp[v]
                  if t < mi:
                      mi = t
                      ans = [v]
                  elif t == mi:
                      ans.append(v)
          return ans
  
  ############
  
  class Solution(object):
    def findRestaurant(self, list1, list2):
      """
      :type list1: List[str]
      :type list2: List[str]
      :rtype: List[str]
      """
      minSum = float("inf")
      ans = []
      d = {}
      for i, name in enumerate(list2):
        d[name] = i
      for i, name in enumerate(list1):
        idxSum = i + d.get(name, float("inf"))
        if idxSum == minSum:
          ans.append(name)
        if idxSum < minSum:
          ans = [name]
          minSum = idxSum
      return ans
  
  

• func findRestaurant(list1 []string, list2 []string) []string {
  	mp := make(map[string]int)
  	for i, v := range list2 {
  		mp[v] = i
  	}
  	mi := 2000
  	var ans []string
  	for i, v := range list1 {
  		if _, ok := mp[v]; ok {
  			t := i + mp[v]
  			if t < mi {
  				ans = []string{v}
  				mi = t
  			} else if t == mi {
  				ans = append(ans, v)
  			}
  		}
  	}
  	return ans
  }
  

• function findRestaurant(list1: string[], list2: string[]): string[] {
      let minI = Infinity;
      const res = [];
      const map = new Map<string, number>(list1.map((s, i) => [s, i]));
      list2.forEach((s, i) => {
          if (map.has(s)) {
              const sumI = i + map.get(s);
              if (sumI <= minI) {
                  if (sumI < minI) {
                      minI = sumI;
                      res.length = 0;
                  }
                  res.push(s);
              }
          }
      });
      return res;
  }
  
  

• use std::collections::HashMap;
  use std::iter::FromIterator;
  
  impl Solution {
      pub fn find_restaurant(list1: Vec<String>, list2: Vec<String>) -> Vec<String> {
          let map: HashMap<String, usize> = HashMap::from_iter(list1.into_iter().zip(0..));
          let mut res = vec![];
          let mut min_i = usize::MAX;
          list2.into_iter().enumerate().for_each(|(i, key)| {
              if map.contains_key(&key) {
                  let sum_i = map.get(&key).unwrap() + i;
                  if sum_i <= min_i {
                      if (sum_i < min_i) {
                          min_i = sum_i;
                          res.clear();
                      }
                      res.push(key);
                  }
              }
          });
          res
      }
  }
  
  

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• RenderScript

• class Solution {
      public String[] findRestaurant(String[] list1, String[] list2) {
          int length1 = list1.length, length2 = list2.length;
          int leastIndexSum = Integer.MAX_VALUE;
          Map<String, Integer> list1Map = new HashMap<String, Integer>();
          Map<Integer, List<String>> indexSumInterestMap = new HashMap<Integer, List<String>>();
          for (int i = 0; i < length1; i++)
              list1Map.put(list1[i], i);
          for (int i = 0; i < length2; i++) {
              String interest = list2[i];
              if (!list1Map.containsKey(interest))
                  continue;
              int indexSum = list1Map.get(interest) + i;
              List<String> interests = indexSumInterestMap.getOrDefault(indexSum, new ArrayList<String>());
              interests.add(interest);
              indexSumInterestMap.put(indexSum, interests);
              if (indexSum < leastIndexSum)
                  leastIndexSum = indexSum;
          }
          List<String> interestsList = indexSumInterestMap.getOrDefault(leastIndexSum, new ArrayList<String>());
          int length = interestsList.size();
          String[] interests = new String[length];
          for (int i = 0; i < length; i++)
              interests[i] = interestsList.get(i);
          return interests;
      }
  }
  
  ############
  
  class Solution {
      public String[] findRestaurant(String[] list1, String[] list2) {
          Map<String, Integer> mp = new HashMap<>();
          for (int i = 0; i < list2.length; ++i) {
              mp.put(list2[i], i);
          }
          List<String> ans = new ArrayList<>();
          int mi = 2000;
          for (int i = 0; i < list1.length; ++i) {
              if (mp.containsKey(list1[i])) {
                  int t = i + mp.get(list1[i]);
                  if (t < mi) {
                      ans = new ArrayList<>();
                      ans.add(list1[i]);
                      mi = t;
                  } else if (t == mi) {
                      ans.add(list1[i]);
                  }
              }
          }
          return ans.toArray(new String[0]);
      }
  }
  

• // OJ: https://leetcode.com/problems/minimum-index-sum-of-two-lists/
  // Time: O(L1 + L2)
  // Space: O(L1)
  class Solution {
  public:
      vector<string> findRestaurant(vector<string>& list1, vector<string>& list2) {
          unordered_map<string, int> m;
          for (int i = 0; i < list1.size(); ++i) m[list1[i]] = i;
          int minSum = INT_MAX;
          vector<string> ans;
          for (int i = 0; i < list2.size() && i <= minSum; ++i) {
              if (m.find(list2[i]) == m.end() || i + m[list2[i]] > minSum) continue;
              if (i + m[list2[i]] < minSum) {
                  ans.clear();
                  minSum = i + m[list2[i]];
              }
              ans.push_back(list2[i]);
          }
          return ans;
      }
  };
  

• class Solution:
      def findRestaurant(self, list1: List[str], list2: List[str]) -> List[str]:
          ans = []
          mp = {v: i for i, v in enumerate(list2)}
          mi = 2000
          for i, v in enumerate(list1):
              if v in mp:
                  t = i + mp[v]
                  if t < mi:
                      mi = t
                      ans = [v]
                  elif t == mi:
                      ans.append(v)
          return ans
  
  ############
  
  class Solution(object):
    def findRestaurant(self, list1, list2):
      """
      :type list1: List[str]
      :type list2: List[str]
      :rtype: List[str]
      """
      minSum = float("inf")
      ans = []
      d = {}
      for i, name in enumerate(list2):
        d[name] = i
      for i, name in enumerate(list1):
        idxSum = i + d.get(name, float("inf"))
        if idxSum == minSum:
          ans.append(name)
        if idxSum < minSum:
          ans = [name]
          minSum = idxSum
      return ans
  
  

• func findRestaurant(list1 []string, list2 []string) []string {
  	mp := make(map[string]int)
  	for i, v := range list2 {
  		mp[v] = i
  	}
  	mi := 2000
  	var ans []string
  	for i, v := range list1 {
  		if _, ok := mp[v]; ok {
  			t := i + mp[v]
  			if t < mi {
  				ans = []string{v}
  				mi = t
  			} else if t == mi {
  				ans = append(ans, v)
  			}
  		}
  	}
  	return ans
  }
  

• function findRestaurant(list1: string[], list2: string[]): string[] {
      let minI = Infinity;
      const res = [];
      const map = new Map<string, number>(list1.map((s, i) => [s, i]));
      list2.forEach((s, i) => {
          if (map.has(s)) {
              const sumI = i + map.get(s);
              if (sumI <= minI) {
                  if (sumI < minI) {
                      minI = sumI;
                      res.length = 0;
                  }
                  res.push(s);
              }
          }
      });
      return res;
  }
  
  

• use std::collections::HashMap;
  use std::iter::FromIterator;
  
  impl Solution {
      pub fn find_restaurant(list1: Vec<String>, list2: Vec<String>) -> Vec<String> {
          let map: HashMap<String, usize> = HashMap::from_iter(list1.into_iter().zip(0..));
          let mut res = vec![];
          let mut min_i = usize::MAX;
          list2.into_iter().enumerate().for_each(|(i, key)| {
              if map.contains_key(&key) {
                  let sum_i = map.get(&key).unwrap() + i;
                  if sum_i <= min_i {
                      if (sum_i < min_i) {
                          min_i = sum_i;
                          res.clear();
                      }
                      res.push(key);
                  }
              }
          });
          res
      }
  }
  
  

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