feat: add solution(s) to lc problem(s): No.67

Author: lingxier

lcof/面试题67. 把字符串转换成整数/Solution.cpp

@@ -0,0 +1,35 @@
+class Solution {
+public:
+    int StrToInt(string str) {
+        int res = 0, bndry = INT_MAX / 10;
+        int i = 0, sign = 1, length = str.size();
+        if(length == 0) {
+            return 0;
+        }
+        // 删除首部空格
+        while(str[i] == ' '){
+            if(++i == length) {
+                return 0;
+            }
+        }
+        //若有负号则标识符号位
+        if(str[i] == '-') {
+            sign = -1;
+        }
+        if(str[i] == '-' || str[i] == '+') {
+            i++;
+        }
+        for(int j = i; j < length; j++) {
+            if(str[j] < '0' || str[j] > '9') {
+                break;
+            }
+            //res>214748364越界；res=214748364且str[j] > '7'越界
+            if(res > bndry || res == bndry && str[j] > '7'){
+                return sign == 1 ? INT_MAX : INT_MIN;
+            }
+            //从左向右遍历数字并更新结果
+            res = res * 10 + (str[j] - '0');
+        }
+        return sign * res;
+    }
+};