Update Minimum_Window_Substring.js

Author: ignacio-chiazzo

LeetcodeProblems/Algorithms/Minimum_Window_Substring.js

@@ -15,6 +15,7 @@ If there is no such window in S that covers all characters in T, return the empt
 If there is such window, you are guaranteed that there will always be only one unique minimum window in S.
 */
 
+// Solution 1
 var minWindow = function (s, t) {
  if (t.length === 0 || s.length < t.length) return "";
 
@@ -67,4 +68,64 @@ var getHash = function (t) {
  return hash;
 };
 
+
+
+// Solution 2
+// Similar idea code slightly different;
+var buildHash = function(t) {
+ let hash = {};
+ let occ = 0;
+ for(var i = 0; i < t.length; i++) {
+ occ = hash[t[i]] == undefined ? 0 : hash[t[i]];
+ hash[t[i]] = occ + 1;
+ }
+ return hash;
+}
+
+var minWindow2 = function(s, t) {
+ var hashT = buildHash(t);
+ var start = 0; 
+ var end = 0;
+ var countLeft = t.length;
+ var minWindow = "";
+ var minWindowLeft = -1;
+ var maxWindowRight = -1;
+
+ while(start < s.length && end < s.length) {
+ if(countLeft > 0) { // window does not contain all elements 
+ if(hashT[s[end]] !== undefined) {
+ hashT[s[end]] = hashT[s[end]] - 1;
+ if(hashT[s[end]] >= 0) {
+ countLeft--;
+ }
+ }
+ 
+ if(countLeft > 0) {
+ end++;
+ }
+ } else { // found window
+ if(minWindowLeft == -1 || ((maxWindowRight - minWindowLeft + 1) > (end - start + 1)) ) {
+ minWindowLeft = start;
+ maxWindowRight = end;
+ }
+ if(hashT[s[start]] !== undefined) {
+ hashT[s[start]] = hashT[s[start]] + 1;
+ if(hashT[s[start]] > 0) {
+ countLeft++;
+ end++;
+ }
+ }
+ start++;
+ }
+ }
+ 
+ if(minWindowLeft > -1) {
+ return s.substring(minWindowLeft, maxWindowRight + 1);
+ }
+ 
+ return "";
+};
+
+
+
 module.exports.minWindow = minWindow;