add problem 29 and test function

Author: supercoderhawk

C/1-50/29-Divide-Two-Integers.c

@@ -0,0 +1,44 @@
+/*
+ * Divide two integers without using multiplication, division and mod operator.
+
+ * If it is overflow, return MAX_INT.
+ * Created by supercoderx on 2017/8/11.
+ */
+#include 
+#include 
+
+int divide(int dividend, int divisor) {
+    if (divisor == 0 || (dividend == INT_MIN) && (divisor == -1)) {
+        return INT_MAX;
+    }
+    if (dividend == INT_MIN && divisor == 1)
+        return INT_MIN;
+    int neg = 0;
+    if ((dividend > 0) ^ (divisor > 0)) {
+        neg = 1;
+    }
+    long long dvd = dividend, dvs = divisor;
+    if (dividend < 0) {
+        dvd = -dvd;
+    }
+    if (divisor < 0) {
+        dvs = -dvs;
+    }
+
+
+    int res = 0;
+    while (dvd >= dvs) {
+        long long temp = dvs, scala = 1;
+        while (dvd >= (temp << 1)) {
+            temp <<= 1;
+            scala <<= 1;
+        }
+        dvd -= temp;
+        res += scala;
+    }
+    return neg == 1 ? -res : res;
+}
+
+void testDivide() {
+    printf("%d", divide(-2147483648, 2));
+}