926 accepted. 4ms > 0ms

Author: aQuaYi

Algorithms/0926.flip-string-to-monotone-increasing/README.md

@@ -0,0 +1,36 @@
+# [926. Flip String to Monotone Increasing](https://leetcode.com/problems/flip-string-to-monotone-increasing/)
+
+A string of `0`s and `1`s is monotone increasing if it consists of some number of `0`s (possibly 0), followed by some number of `1`s (also possibly 0.)
+
+We are given a string `S` of `0`s and `1`s, and we may flip any `0` to a `1` or a `1` to a `0`.
+
+Return the minimum number of flips to make `S` monotone increasing.
+
+Example 1:
+
+```text
+Input: "00110"
+Output: 1
+Explanation: We flip the last digit to get 00111.
+```
+
+Example 2:
+
+```text
+Input: "010110"
+Output: 2
+Explanation: We flip to get 011111, or alternatively 000111.
+```
+
+Example 3:
+
+```text
+Input: "00011000"
+Output: 2
+Explanation: We flip to get 00000000.
+```
+
+Note:
+
+1. `1 <= S.length <= 20000`
+1. `S` only consists of `0` and `1` characters.

Algorithms/0926.flip-string-to-monotone-increasing/flip-string-to-monotone-increasing.go

@@ -0,0 +1,41 @@
+package problem0926
+
+func minFlipsMonoIncr(S string) int {
+	size := len(S)
+
+	ones := make([]int, 0, size)
+	zeros := make([]int, 0, size)
+
+	for i := 0; i < size; i++ {
+		if S[i] == '1' {
+			ones = append(ones, i)
+		} else {
+			zeros = append(zeros, i)
+		}
+	}
+
+	oneSize := len(ones)
+	zeroSize := len(zeros)
+
+	res := size
+
+	i, j := 0, 0
+	for i < oneSize {
+		for j < zeroSize && zeros[j] < ones[i] {
+			j++
+		}
+		res = min(res, i+zeroSize-j)
+		i++
+	}
+
+	res = min(res, oneSize)
+
+	return res
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}

Algorithms/0926.flip-string-to-monotone-increasing/flip-string-to-monotone-increasing_test.go

@@ -0,0 +1,57 @@
+package problem0926
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// tcs is testcase slice
+var tcs = []struct {
+	S   string
+	ans int
+}{
+
+	{
+		"01000011110",
+		2,
+	},
+
+	{
+		"00110",
+		1,
+	},
+
+	{
+		"00110",
+		1,
+	},
+
+	{
+		"010110",
+		2,
+	},
+
+	{
+		"00011000",
+		2,
+	},
+
+	// 可以有多个 testcase
+}
+
+func Test_minFlipsMonoIncr(t *testing.T) {
+	ast := assert.New(t)
+
+	for _, tc := range tcs {
+		ast.Equal(tc.ans, minFlipsMonoIncr(tc.S), "输入:%v", tc)
+	}
+}
+
+func Benchmark_minFlipsMonoIncr(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range tcs {
+			minFlipsMonoIncr(tc.S)
+		}
+	}
+}