sortedCount.swift

func sortedCount(of input: [String]) -> [(String, Int)] {
    input.reduce(into: [String: (index: Int, count: Int)]()) { state, str in
        var info = state[str] ?? (index: state.count, count: 0)
        info.count += 1
        state[str] = info
    }.sorted { lhs, rhs in
        lhs.value.index < rhs.value.index
    }.map {
        ($0.key, $0.value.count) 
    }
}

print(sortedCount(of: ["Wake up", "Do physics", "Play with a pet", "Do physics"]))
// [("Wake up", 1), ("Do physics", 2), ("Play with a pet", 1)]