Create Maximum_Product_Subarray.cc

DP. In order to deal with the negatives, it needs to mark down the maximum(>0) and minimum result(<0) at the same time.

Author: iphkwan

Maximum_Product_Subarray.cc

@@ -0,0 +1,17 @@
+class Solution {
+public:
+    int maxProduct(int A[], int n) {
+        if (n <= 0) return 0;
+        int iMaxProductEndByPrePos = A[0], iMaxProductEndByCurrentPos;
+        int iMinProductEndByPrePos = A[0], iMinProductEndByCurrentPos;
+        int ret = A[0];
+        for (int i = 1; i < n; i++) {
+            iMaxProductEndByCurrentPos = max(max(iMaxProductEndByPrePos * A[i], iMinProductEndByPrePos * A[i]), A[i]);
+            iMinProductEndByCurrentPos = min(min(iMaxProductEndByPrePos * A[i], iMinProductEndByPrePos * A[i]), A[i]);
+            ret = max(ret, iMaxProductEndByCurrentPos);
+            iMaxProductEndByPrePos = iMaxProductEndByCurrentPos;
+            iMinProductEndByPrePos = iMinProductEndByCurrentPos;
+        }
+        return ret;
+    }
+};