Create count-pairs-of-equal-substrings-with-minimum-difference.cpp

Author: kamyu104

C++/count-pairs-of-equal-substrings-with-minimum-difference.cpp

@@ -0,0 +1,28 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int countQuadruples(string firstString, string secondString) {
+        vector<int> lookup1(26, -1);
+        for (int j = size(firstString) - 1; j >= 0; --j) {
+            lookup1[firstString[j] - 'a'] = j;
+        }
+        vector<int> lookup2(26, -1);
+        for (int a = 0; a < size(secondString); ++a) {
+            lookup2[secondString[a] - 'a'] = a;
+        }
+        int result = 0, diff = numeric_limits<int>::max();
+        for (int i = 0; i < 26; ++i) {
+            if (lookup1[i] == -1 || lookup2[i] == -1) {
+                continue;
+            }
+            if (lookup1[i] - lookup2[i] < diff) {
+                diff = lookup1[i] - lookup2[i];
+                result = 0;
+            }                
+            result += (lookup1[i] - lookup2[i] == diff);                
+        }
+        return result;
+    }
+};