feat: add solutions to lc problem: No.0415

No.0415.Add Strings

Author: yanglbme

solution/0400-0499/0415.Add Strings/README.md

@@ -57,6 +57,8 @@
 
 时间复杂度 $O(max(m, n))$，其中 $m$ 和 $n$ 分别是两个字符串的长度。忽略答案字符串的空间消耗，空间复杂度 $O(1)$。
 
+以下代码还实现了字符串相减，参考 `subStrings(num1, num2)` 函数。
+
 <!-- tabs:start -->
 
 ### **Python3**
@@ -76,6 +78,25 @@ class Solution:
             ans.append(str(v))
             i, j = i - 1, j - 1
         return "".join(ans[::-1])
+
+    def subStrings(self, num1: str, num2: str) -> str:
+        m, n = len(num1), len(num2)
+        neg = m < n or (m == n and num1 < num2)
+        if neg:
+            num1, num2 = num2, num1
+        i, j = len(num1) - 1, len(num2) - 1
+        ans = []
+        c = 0
+        while i >= 0:
+            c = int(num1[i]) - c - (0 if j < 0 else int(num2[j]))
+            ans.append(str((c + 10) % 10))
+            c = 1 if c < 0 else 0
+            i, j = i - 1, j - 1
+        while len(ans) > 1 and ans[-1] == '0':
+            ans.pop()
+        if neg:
+            ans.append('-')
+        return ''.join(ans[::-1])
 ```
 
 ### **Java**
@@ -96,6 +117,30 @@ class Solution {
         }
         return ans.reverse().toString();
     }
+
+    public String subStrings(String num1, String num2) {
+        int m = num1.length(), n = num2.length();
+        boolean neg = m < n || (m == n && num1.compareTo(num2) < 0);
+        if (neg) {
+            String t = num1;
+            num1 = num2;
+            num2 = t;
+        }
+        int i = num1.length() - 1, j = num2.length() - 1;
+        StringBuilder ans = new StringBuilder();
+        for (int c = 0; i >= 0; --i, --j) {
+            c = (num1.charAt(i) - '0') - c - (j < 0 ? 0 : num2.charAt(j) - '0');
+            ans.append((c + 10) % 10);
+            c = c < 0 ? 1 : 0;
+        }
+        while (ans.length() > 1 && ans.charAt(ans.length() - 1) == '0') {
+            ans.deleteCharAt(ans.length() - 1);
+        }
+        if (neg) {
+            ans.append('-');
+        }
+        return ans.reverse().toString();
+    }
 }
 ```
 
@@ -117,6 +162,29 @@ public:
         reverse(ans.begin(), ans.end());
         return ans;
     }
+
+    string subStrings(string num1, string num2) {
+        int m = num1.size(), n = num2.size();
+        bool neg = m < n || (m == n && num1 < num2);
+        if (neg) {
+            swap(num1, num2);
+        }
+        int i = num1.size() - 1, j = num2.size() - 1;
+        string ans;
+        for (int c = 0; i >= 0; --i, --j) {
+            c = (num1[i] - '0') - c - (j < 0 ? 0 : num2[j] - '0');
+            ans += to_string((c + 10) % 10);
+            c = c < 0 ? 1 : 0;
+        }
+        while (ans.size() > 1 && ans.back() == '0') {
+            ans.pop_back();
+        }
+        if (neg) {
+            ans.push_back('-');
+        }
+        reverse(ans.begin(), ans.end());
+        return ans;
+    }
 };
 ```
 
@@ -141,6 +209,38 @@ func addStrings(num1 string, num2 string) string {
 	}
 	return string(ans)
 }
+
+func subStrings(num1 string, num2 string) string {
+	m, n := len(num1), len(num2)
+	neg := m < n || (m == n && num1 < num2)
+	if neg {
+		num1, num2 = num2, num1
+	}
+	i, j := len(num1)-1, len(num2)-1
+	ans := []byte{}
+	for c := 0; i >= 0; i, j = i-1, j-1 {
+		c = int(num1[i]-'0') - c
+		if j >= 0 {
+			c -= int(num2[j] - '0')
+		}
+		ans = append(ans, byte((c+10)%10+'0'))
+		if c < 0 {
+			c = 1
+		} else {
+			c = 0
+		}
+	}
+	for len(ans) > 1 && ans[len(ans)-1] == '0' {
+		ans = ans[:len(ans)-1]
+	}
+	if neg {
+		ans = append(ans, '-')
+	}
+	for i, j := 0, len(ans)-1; i < j; i, j = i+1, j-1 {
+		ans[i], ans[j] = ans[j], ans[i]
+	}
+	return string(ans)
+}
 ```
 
 ### **JavaScript**
@@ -163,6 +263,40 @@ var addStrings = function (num1, num2) {
     }
     return ans.reverse().join('');
 };
+
+/**
+ * @param {string} num1
+ * @param {string} num2
+ * @return {string}
+ */
+var subStrings = function (num1, num2) {
+    const m = num1.length;
+    const n = num2.length;
+    const neg = m < n || (m == n && num1 < num2);
+    if (neg) {
+        const t = num1;
+        num1 = num2;
+        num2 = t;
+    }
+    let i = num1.length - 1;
+    let j = num2.length - 1;
+    const ans = [];
+    for (let c = 0; i >= 0; --i, --j) {
+        c = parseInt(num1.charAt(i), 10) - c;
+        if (j >= 0) {
+            c -= parseInt(num2.charAt(j), 10);
+        }
+        ans.push((c + 10) % 10);
+        c = c < 0 ? 1 : 0;
+    }
+    while (ans.length > 1 && ans[ans.length - 1] == '0') {
+        ans.pop();
+    }
+    if (neg) {
+        ans.push('-');
+    }
+    return ans.reverse().join('');
+};
 ```
 
 ### **TypeScript**

solution/0400-0499/0415.Add Strings/README_EN.md

@@ -58,6 +58,25 @@ class Solution:
             ans.append(str(v))
             i, j = i - 1, j - 1
         return "".join(ans[::-1])
+    
+    def subStrings(self, num1: str, num2: str) -> str:
+        m, n = len(num1), len(num2)
+        neg = m < n or (m == n and num1 < num2)
+        if neg:
+            num1, num2 = num2, num1
+        i, j = len(num1) - 1, len(num2) - 1
+        ans = []
+        c = 0
+        while i >= 0:
+            c = int(num1[i]) - c - (0 if j < 0 else int(num2[j]))
+            ans.append(str((c + 10) % 10))
+            c = 1 if c < 0 else 0
+            i, j = i - 1, j - 1
+        while len(ans) > 1 and ans[-1] == '0':
+            ans.pop()
+        if neg:
+            ans.append('-')
+        return ''.join(ans[::-1])
 ```
 
 ### **Java**
@@ -76,6 +95,30 @@ class Solution {
         }
         return ans.reverse().toString();
     }
+
+    public String subStrings(String num1, String num2) {
+        int m = num1.length(), n = num2.length();
+        boolean neg = m < n || (m == n && num1.compareTo(num2) < 0);
+        if (neg) {
+            String t = num1;
+            num1 = num2;
+            num2 = t;
+        }
+        int i = num1.length() - 1, j = num2.length() - 1;
+        StringBuilder ans = new StringBuilder();
+        for (int c = 0; i >= 0; --i, --j) {
+            c = (num1.charAt(i) - '0') - c - (j < 0 ? 0 : num2.charAt(j) - '0');
+            ans.append((c + 10) % 10);
+            c = c < 0 ? 1 : 0;
+        }
+        while (ans.length() > 1 && ans.charAt(ans.length() - 1) == '0') {
+            ans.deleteCharAt(ans.length() - 1);
+        }
+        if (neg) {
+            ans.append('-');
+        }
+        return ans.reverse().toString();
+    }
 }
 ```
 
@@ -97,6 +140,29 @@ public:
         reverse(ans.begin(), ans.end());
         return ans;
     }
+
+    string subStrings(string num1, string num2) {
+        int m = num1.size(), n = num2.size();
+        bool neg = m < n || (m == n && num1 < num2);
+        if (neg) {
+            swap(num1, num2);
+        }
+        int i = num1.size() - 1, j = num2.size() - 1;
+        string ans;
+        for (int c = 0; i >= 0; --i, --j) {
+            c = (num1[i] - '0') - c - (j < 0 ? 0 : num2[j] - '0');
+            ans += to_string((c + 10) % 10);
+            c = c < 0 ? 1 : 0;
+        }
+        while (ans.size() > 1 && ans.back() == '0') {
+            ans.pop_back();
+        }
+        if (neg) {
+            ans.push_back('-');
+        }
+        reverse(ans.begin(), ans.end());
+        return ans;
+    }
 };
 ```
 
@@ -121,6 +187,38 @@ func addStrings(num1 string, num2 string) string {
 	}
 	return string(ans)
 }
+
+func subStrings(num1 string, num2 string) string {
+	m, n := len(num1), len(num2)
+	neg := m < n || (m == n && num1 < num2)
+	if neg {
+		num1, num2 = num2, num1
+	}
+	i, j := len(num1)-1, len(num2)-1
+	ans := []byte{}
+	for c := 0; i >= 0; i, j = i-1, j-1 {
+		c = int(num1[i]-'0') - c
+		if j >= 0 {
+			c -= int(num2[j] - '0')
+		}
+		ans = append(ans, byte((c+10)%10+'0'))
+		if c < 0 {
+			c = 1
+		} else {
+			c = 0
+		}
+	}
+	for len(ans) > 1 && ans[len(ans)-1] == '0' {
+		ans = ans[:len(ans)-1]
+	}
+	if neg {
+		ans = append(ans, '-')
+	}
+	for i, j := 0, len(ans)-1; i < j; i, j = i+1, j-1 {
+		ans[i], ans[j] = ans[j], ans[i]
+	}
+	return string(ans)
+}
 ```
 
 ### **JavaScript**
@@ -143,6 +241,40 @@ var addStrings = function (num1, num2) {
     }
     return ans.reverse().join('');
 };
+
+/**
+ * @param {string} num1
+ * @param {string} num2
+ * @return {string}
+ */
+var subStrings = function (num1, num2) {
+    const m = num1.length;
+    const n = num2.length;
+    const neg = m < n || (m == n && num1 < num2);
+    if (neg) {
+        const t = num1;
+        num1 = num2;
+        num2 = t;
+    }
+    let i = num1.length - 1;
+    let j = num2.length - 1;
+    const ans = [];
+    for (let c = 0; i >= 0; --i, --j) {
+        c = parseInt(num1.charAt(i), 10) - c;
+        if (j >= 0) {
+            c -= parseInt(num2.charAt(j), 10);
+        }
+        ans.push((c + 10) % 10);
+        c = c < 0 ? 1 : 0;
+    }
+    while (ans.length > 1 && ans[ans.length - 1] == '0') {
+        ans.pop();
+    }
+    if (neg) {
+        ans.push('-');
+    }
+    return ans.reverse().join('');
+};
 ```
 
 ### **TypeScript**

solution/0400-0499/0415.Add Strings/Solution.cpp

@@ -13,4 +13,27 @@ class Solution {
         reverse(ans.begin(), ans.end());
         return ans;
     }
+
+    string subStrings(string num1, string num2) {
+        int m = num1.size(), n = num2.size();
+        bool neg = m < n || (m == n && num1 < num2);
+        if (neg) {
+            swap(num1, num2);
+        }
+        int i = num1.size() - 1, j = num2.size() - 1;
+        string ans;
+        for (int c = 0; i >= 0; --i, --j) {
+            c = (num1[i] - '0') - c - (j < 0 ? 0 : num2[j] - '0');
+            ans += to_string((c + 10) % 10);
+            c = c < 0 ? 1 : 0;
+        }
+        while (ans.size() > 1 && ans.back() == '0') {
+            ans.pop_back();
+        }
+        if (neg) {
+            ans.push_back('-');
+        }
+        reverse(ans.begin(), ans.end());
+        return ans;
+    }
 };