feat: 134 greedy

Author: chen-shiwei

leetcode/134.加油站/canCompleteCircuit.go

@@ -0,0 +1,36 @@
+package _134_加油站
+
+func canCompleteCircuit(gas []int, cost []int) int {
+	l1 := len(gas)
+
+	for i := 0; i < l1; i++ {
+		var ans = gas[i] - cost[i]
+		idx := (i + 1) % l1
+		for idx != i && ans > 0 {
+			ans += gas[idx] - cost[idx]
+			idx = (idx + 1) % l1
+		}
+		if ans >= 0 && idx == i {
+			return i
+		}
+	}
+	return -1
+}
+
+func canCompleteCircuitWithGreedy(gas []int, cost []int) int {
+	l := len(gas)
+	var curSum, sum, idx int
+	for i := 0; i < l; i++ {
+		sum += gas[i] - cost[i]
+		curSum += gas[i] - cost[i]
+		if curSum < 0 {
+			idx = i + 1
+			curSum = 0
+		}
+	}
+	if sum < 0 {
+		return -1
+	}
+
+	return idx
+}

leetcode/134.加油站/canCompleteCircuit_test.go

@@ -0,0 +1,28 @@
+package _134_加油站
+
+import "testing"
+
+func Test_canCompleteCircuit(t *testing.T) {
+	type args struct {
+		gas  []int
+		cost []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{name: `gas  = [1,2,3,4,5]
+cost = [3,4,5,1,2]`, args: args{
+			gas:  []int{1, 2, 3, 4, 5},
+			cost: []int{3, 4, 5, 1, 2},
+		}, want: 3},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := canCompleteCircuitWithGreedy(tt.args.gas, tt.args.cost); got != tt.want {
+				t.Errorf("canCompleteCircuit() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}