规范格式

leetcode/0402.Remove-K-Digits/402. Remove K Digits.go

@@ -0,0 +1,23 @@
+package leetcode
+
+func removeKdigits(num string, k int) string {
+	if k == len(num) {
+		return "0"
+	}
+	res := []byte{}
+	for i := 0; i < len(num); i++ {
+		c := num[i]
+		for k > 0 && len(res) > 0 && c < res[len(res)-1] {
+			res = res[:len(res)-1]
+			k--
+		}
+		res = append(res, c)
+	}
+	res = res[:len(res)-k]
+
+	// trim leading zeros
+	for len(res) > 1 && res[0] == '0' {
+		res = res[1:]
+	}
+	return string(res)
+}

leetcode/0402.Remove-K-Digits/402. Remove K Digits_test.go

@@ -0,0 +1,77 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question402 struct {
+	para402
+	ans402
+}
+
+// para 是参数
+// one 代表第一个参数
+type para402 struct {
+	num string
+	k   int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans402 struct {
+	one string
+}
+
+func Test_Problem402(t *testing.T) {
+
+	qs := []question402{
+		question402{
+			para402{"10", 1},
+			ans402{"0"},
+		},
+
+		question402{
+			para402{"1111111", 3},
+			ans402{"1111"},
+		},
+
+		question402{
+			para402{"5337", 2},
+			ans402{"33"},
+		},
+
+		question402{
+			para402{"112", 1},
+			ans402{"11"},
+		},
+
+		question402{
+			para402{"1432219", 3},
+			ans402{"1219"},
+		},
+
+		question402{
+			para402{"10200", 1},
+			ans402{"200"},
+		},
+
+		question402{
+			para402{"10", 2},
+			ans402{"0"},
+		},
+
+		question402{
+			para402{"19", 2},
+			ans402{"0"},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 402------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans402, q.para402
+		fmt.Printf("【input】:%v       【output】:%v\n", p, removeKdigits(p.num, p.k))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/0402.Remove-K-Digits/README.md

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+# [402. Remove K Digits](https://leetcode.com/problems/remove-k-digits/)
+
+## 题目
+
+Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible.
+
+Note:
+
+- The length of num is less than 10002 and will be ≥ k.
+- The given num does not contain any leading zero.
+
+
+Example 1:
+
+```c
+Input: num = "1432219", k = 3
+Output: "1219"
+Explanation: Remove the three digits 4, 3, and 2 to form the new number 1219 which is the smallest.
+```
+
+Example 2:
+
+```c
+Input: num = "10200", k = 1
+Output: "200"
+Explanation: Remove the leading 1 and the number is 200. Note that the output must not contain leading zeroes.
+```
+
+Example 3:
+
+```c
+Input: num = "10", k = 2
+Output: "0"
+Explanation: Remove all the digits from the number and it is left with nothing which is 0.
+```
+
+## 题目大意
+
+给定一个以字符串表示的非负整数 num，移除这个数中的 k 位数字，使得剩下的数字最小。
+
+注意:
+
+- num 的长度小于 10002 且 ≥ k。
+- num 不会包含任何前导零。
+
+
+## 解题思路
+
+从开头扫 num 每一位，依次入栈，当新来的数字比栈顶元素小，就依次往前移除掉所有比这个新来数字大的数字。注意最后要求剩下的数字最小，如果最后剩下的数字超过了 K 位，取前 K 位必然是最小的(因为如果后 K 位有比前 K 位更小的值的话，会把前面大的数字踢除的)
+
+注意，虽然 num 不会包含前导 0，但是最终删掉中间的数字以后，比如删掉 0 前面的所有数字以后，前导 0 就会出来，最终输出的时候要去掉前导 0 。