sum of two integers solution

Author: yhkee0404

sum-of-two-integers/yhkee0404.dart

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+class Solution {
+  int getSum(int a, int b) {
+    int ans = 0;
+    // for (int i = 0, carry = 0, ai, bi, u = 1; i != 64 && (carry | a | b) != 0; i++, a >>>= 1, b >>>= 1, u <<= 1) { // significand 53 bits but u has only 1 bit
+    for (int i = 0, carry = 0, ai, bi, u = 1; i != 32 && (carry | a | b) != 0; i++, a >>= 1, b >>= 1, u <<= 1) {
+        ai = a & 1;
+        bi = b & 1;
+        if ((ai & bi) == 1) {
+            if (carry == 1) {
+                ans |= u;
+            }
+            carry = 1;
+        } else if ((ai ^ bi) == 1) {
+            if (carry == 0) {
+                ans |= u;
+            }
+        } else {
+            if (carry == 1) {
+                ans |= u;
+            }
+            carry = 0;
+        }
+    }
+    // return ans;
+    return (ans & 0x80000000) != 0 ? ans | ~ 0xFFFFFFFF : ans;
+  }
+}