Create suffixArray

Author: dabhitapan

Arrays/suffixArray

@@ -0,0 +1,37 @@
+// Build a suffix array in O(n^2*log n);
+// kinda too much, but now you can search for a pattern in O(n*log n) where `n` is number of characters in `str`
+//
+function searchPattern(str) {
+    var strLen = str.length;
+    var suffixArray = new Array(strLen);
+    var suffixes = new Array(strLen);
+  
+    for (var i = strLen-1; i >= 0; i--) {
+      suffixes[i] = [i, str.substr(i)];
+    }
+   
+    suffixes.sort(function(a, b) { 
+      return a[1] < b[1] ? -1 : 1;
+    });
+   
+    for (var i = 0; i < strLen; i++) {
+      suffixArray[i] = suffixes[i][0];
+    }
+    
+    return function(pattern) {
+      var l = 0;
+      var r = strLen-1;
+      while (l <= r) {
+        var mid = (l + r) >> 1;
+        var cmp = pattern.localeCompare( suffixes[suffixArray[mid]][1] );
+        if (cmp === 0) {
+          return mid;
+        } else if (cmp > 0) {
+          l = mid + 1;
+        } else {
+          r = mid - 1;
+        }
+      }
+      return -1;
+    }
+  }